[ONOS-4797] Implement the Driver for handling Arista switch

Arista switch with its recent network OS, EOS, supports remote configuration & control. The protocol for this is Arista's proprietary but REST style.
Since ONOS has already REST southbound protocol, the control of Arista switch can be easily done by using this.

- Implemnted driver Loader for Arista switch
- Implemented DeviceDescriptionDiscovery for Arista switch
- [Deleted] Implemented the method sending post to Arista switch and return the result as a String

Change-Id: I9d4b8f0d707361949ff530ff414adb0437ae87d9
diff --git a/drivers/arista/features.xml b/drivers/arista/features.xml
new file mode 100755
index 0000000..74a9e87
--- /dev/null
+++ b/drivers/arista/features.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<!--
+  ~ Copyright 2016 Open Networking Laboratory
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<features xmlns="http://karaf.apache.org/xmlns/features/v1.2.0" name="${project.artifactId}-${project.version}">
+    <feature name="${project.artifactId}" version="${project.version}"
+             description="${project.description}">
+        <feature>onos-api</feature>
+        <bundle>mvn:${project.groupId}/${project.artifactId}/${project.version}</bundle>
+        <bundle>mvn:${project.groupId}/onos-drivers-utilities/${project.version}</bundle>
+    </feature>
+</features>