Updated api-manager.xml to add configuration on external api stores APIMANAGER-1446

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180785 a5903396-d722-0410-b921-86c7d4935375
Updated sql scripts to add new db table  on published external api stores APIMANAGER-1446

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@180786 a5903396-d722-0410-b921-86c7d4935375