[ONOS-3603] Implement REST API for Group query, insert, delete

* Implement decoding feature for GroupBucketCodec and GroupCodec
* Implement GroupsWebResource
* Add unit test for GroupBucketCodec and GroupCodec
* Add unit test for GroupsWebResource
* Add group insertion json example
* Add Swagger doc

Change-Id: Ie58cba2e1af996c7b8652a55d9ef0c27207beafc
diff --git a/web/api/src/main/resources/definitions/Groups.json b/web/api/src/main/resources/definitions/Groups.json
new file mode 100644
index 0000000..517c564
--- /dev/null
+++ b/web/api/src/main/resources/definitions/Groups.json
@@ -0,0 +1,124 @@
+{
+  "type": "object",
+  "title": "groups",
+  "required": [
+    "groups"
+  ],
+  "properties": {
+    "groups": {
+      "type": "array",
+      "xml": {
+        "name": "groups",
+        "wrapped": true
+      },
+      "items": {
+        "type": "object",
+        "title": "group",
+        "required": [
+          "id",
+          "state",
+          "life",
+          "packets",
+          "bytes",
+          "referenceCount",
+          "type",
+          "deviceId",
+          "buckets"
+        ],
+        "properties": {
+          "id": {
+            "type": "string",
+            "example": "1"
+          },
+          "state": {
+            "type": "string",
+            "example": "PENDING_ADD"
+          },
+          "life": {
+            "type": "integer",
+            "format": "int64",
+            "example": 69889
+          },
+          "packets": {
+            "type": "integer",
+            "format": "int64",
+            "example": 22546
+          },
+          "bytes": {
+            "type": "integer",
+            "format": "int64",
+            "example": 1826226
+          },
+          "referenceCount": {
+            "type": "integer",
+            "format": "int64",
+            "example": 1826226
+          },
+          "type": {
+            "type": "string",
+            "example": "ALL"
+          },
+          "deviceId": {
+            "type": "string",
+            "example": "of:0000000000000003"
+          },
+          "buckets": {
+            "type": "array",
+            "xml": {
+              "name": "buckets",
+              "wrapped": true
+            },
+            "items": {
+              "type": "object",
+              "title": "buckets",
+              "required": [
+                "treatment",
+                "weight",
+                "watchPort",
+                "watchGroup"
+              ],
+              "properties": {
+                "treatment": {
+                  "type": "object",
+                  "title": "treatment",
+                  "required": [
+                    "instructions",
+                    "deferred"
+                  ],
+                  "properties": {
+                    "instructions": {
+                      "type": "array",
+                      "title": "treatment",
+                      "required": [
+                        "properties",
+                        "port"
+                      ],
+                      "items": {
+                        "type": "object",
+                        "title": "instructions",
+                        "required": [
+                          "type",
+                          "port"
+                        ],
+                        "properties": {
+                          "type": {
+                            "type": "string",
+                            "example": "OUTPUT"
+                          },
+                          "port": {
+                            "type": "string",
+                            "example": "2"
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/web/api/src/main/resources/definitions/GroupsPost.json b/web/api/src/main/resources/definitions/GroupsPost.json
new file mode 100644
index 0000000..f096201
--- /dev/null
+++ b/web/api/src/main/resources/definitions/GroupsPost.json
@@ -0,0 +1,84 @@
+{
+  "type": "object",
+  "title": "group",
+  "required": [
+    "type",
+    "deviceId",
+    "appCookie",
+    "groupId",
+    "buckets"
+  ],
+  "properties": {
+    "type": {
+      "type": "string",
+      "example": "ALL"
+    },
+    "deviceId": {
+      "type": "string",
+      "example": "of:0000000000000001"
+    },
+    "appCookie": {
+      "type": "string",
+      "example": "1"
+    },
+    "groupId": {
+      "type": "string",
+      "example": "1"
+    },
+    "buckets": {
+      "type": "array",
+      "xml": {
+        "name": "buckets",
+        "wrapped": true
+      },
+      "items": {
+        "type": "object",
+        "title": "buckets",
+        "required": [
+          "treatment",
+          "weight",
+          "watchPort",
+          "watchGroup"
+        ],
+        "properties": {
+          "treatment": {
+            "type": "object",
+            "title": "treatment",
+            "required": [
+              "instructions",
+              "deferred"
+            ],
+            "properties": {
+              "instructions": {
+                "type": "array",
+                "title": "treatment",
+                "required": [
+                  "properties",
+                  "port"
+                ],
+                "items": {
+                  "type": "object",
+                  "title": "instructions",
+                  "required": [
+                    "type",
+                    "port"
+                  ],
+                  "properties": {
+                    "type": {
+                      "type": "string",
+                      "example": "OUTPUT"
+                    },
+                    "port": {
+                      "type": "string",
+                      "example": "2"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
\ No newline at end of file