change mapping grammer

git-svn-id: https://svn.wso2.org/repos/wso2/trunk/tools@185190 a5903396-d722-0410-b921-86c7d4935375
modify datamapper core

git-svn-id: https://svn.wso2.org/repos/wso2/trunk/tools@185191 a5903396-d722-0410-b921-86c7d4935375