Improve coverage for Intents REST API test

Also, added @Provider annotation to all exception mappers so
the Jersey unit test framework will apply them during
testing.

Change-Id: Ifd9237de2e159cd97b64dcb9bde4a66f14bd0dfc
diff --git a/web/api/src/main/java/org/onosproject/rest/exceptions/WebApplicationExceptionMapper.java b/web/api/src/main/java/org/onosproject/rest/exceptions/WebApplicationExceptionMapper.java
index f47e604..86d8434 100644
--- a/web/api/src/main/java/org/onosproject/rest/exceptions/WebApplicationExceptionMapper.java
+++ b/web/api/src/main/java/org/onosproject/rest/exceptions/WebApplicationExceptionMapper.java
@@ -17,10 +17,12 @@
 
 import javax.ws.rs.WebApplicationException;
 import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.Provider;
 
 /**
  * Exception mapper for WebApplicationExceptions.
  */
+@Provider
 public class WebApplicationExceptionMapper extends AbstractMapper<WebApplicationException> {
 
     /**