Created new Widget REST model and interface

git-svn-id: http://svn.apache.org/repos/asf/rave/trunk@1540803 13f79535-47bb-0310-9956-ffa450edef68
Created new Widget Service implementation (RAVE-1077)

git-svn-id: http://svn.apache.org/repos/asf/rave/trunk@1540829 13f79535-47bb-0310-9956-ffa450edef68
Added widget service to the application context (RAVE-1077)

git-svn-id: http://svn.apache.org/repos/asf/rave/trunk@1540830 13f79535-47bb-0310-9956-ffa450edef68