REST API for pseudowire addition / deletion.

Refactored pseudowire code to use REST in order
to add or delete pseudowires individually. Previous implementation
used the network configuration, which is now completely
removed from the code. Further, I re-organized the code
and create a utility class that holds all the necessary
functionality for verifying pseudowires.

Further, I removed all mastership checks in the pw code
since now a specific pseudowire creation is sent to a single
instance, which will handle the call.

Change-Id: I1eb5e7cc7730ad792ea84dd389475768153e2b68
diff --git a/web/src/main/java/org/onosproject/segmentrouting/package-info.java b/web/src/main/java/org/onosproject/segmentrouting/package-info.java
index ff9555e..1d50ba9 100644
--- a/web/src/main/java/org/onosproject/segmentrouting/package-info.java
+++ b/web/src/main/java/org/onosproject/segmentrouting/package-info.java
@@ -15,6 +15,6 @@
  */
 
 /**
- * Segment routing application components.
+ * Segment routing REST implementation.
  */
 package org.onosproject.segmentrouting.web;
\ No newline at end of file