refactored caching core

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@178834 a5903396-d722-0410-b921-86c7d4935375
refactored caching impl

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@178835 a5903396-d722-0410-b921-86c7d4935375