OAK-960 -  Provide an interceptor for SessionOperations

Initial implementation

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1515395 13f79535-47bb-0310-9956-ffa450edef68
OAK-960 -  Provide an interceptor for SessionOperations

Updating javadoc

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1515396 13f79535-47bb-0310-9956-ffa450edef68