adding OAuth based authenticator for SCIM

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@175667 a5903396-d722-0410-b921-86c7d4935375
fixing test failures

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@175668 a5903396-d722-0410-b921-86c7d4935375
some code refactoring

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@175669 a5903396-d722-0410-b921-86c7d4935375