BugFix: Allow to specify mastership role through REST API

In current implementation, swagger doc does match with codec impl.
With this commit, we can assign an exact mastership role for a
device through REST API.

Change-Id: I5cb3f8d478f8fe3eb22f12fc5254ed8a400d5b56

@@ -4,7 +4,7 @@
   "required": [
     "deviceId",
     "nodeId",
-    "mastershipRole"
+    "role"
   ],
   "properties": {
     "deviceId": {
@@ -15,7 +15,7 @@
       "type": "string",
       "example": "1"
     },
-    "mastershipRole": {
+    "role": {
       "type": "string",
       "example": "MASTER"
     }

 {
   "type": "object",
-  "title": "mastershipRole",
+  "title": "role",
   "required": [
     "role"
   ],