Adding gitblit to the setup script


git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180276 a5903396-d722-0410-b921-86c7d4935375
ayaskanthas patch given to BAM-1269

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180277 a5903396-d722-0410-b921-86c7d4935375