Added some Javadoc comments.

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@179899 a5903396-d722-0410-b921-86c7d4935375
Deleted unwanted class MessageStores.java.

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@179900 a5903396-d722-0410-b921-86c7d4935375