adding new gitblit user service implementation

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180715 a5903396-d722-0410-b921-86c7d4935375
Fixing the RepositoryAuthenticationService.



git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180716 a5903396-d722-0410-b921-86c7d4935375
modifying methods to use tenant domain

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180717 a5903396-d722-0410-b921-86c7d4935375