refactoring code to add default-p2-repository: Adding the pre-defined p2-repo without loading it to validate whether it's an available repository. Loading the default repo at feature-manager index.page is expensive and effects initial page-loading time

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/kernel/trunk@163069 a5903396-d722-0410-b921-86c7d4935375