JCR-3788 - S3DataStore require to set endpoint for thirdparty cloud provider (IDCF)

Applied the patch from Shashank.  The region would now be specified before bucket exist call is made

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/trunk@1601550 13f79535-47bb-0310-9956-ffa450edef68