[ONOS-3618] Implement REST API for Meter query, insert, delete

* Implement encode & decode method for MeterBandCodec & MeterCodec
* Implement MetersWebResource
* Add unit test for MeterBandCodec & MeterCodec
* Add unit test for MetersWebResource
* Add meter insertion json example
* Add Swagger doc

Change-Id: I07284c6678c08b3cb9e109e86ffb2cf28bf36447
diff --git a/core/api/src/main/java/org/onosproject/net/meter/Band.java b/core/api/src/main/java/org/onosproject/net/meter/Band.java
index 2bfafad..0144a38 100644
--- a/core/api/src/main/java/org/onosproject/net/meter/Band.java
+++ b/core/api/src/main/java/org/onosproject/net/meter/Band.java
@@ -51,7 +51,7 @@
      *
      * @return the long value of the size
      */
-    long burst();
+    Long burst();
 
     /**
      * Only meaningful in the case of a REMARK band type.
@@ -60,7 +60,7 @@
      *
      * @return a short value
      */
-    short dropPrecedence();
+    Short dropPrecedence();
 
     /**
      * Signals the type of band to create.