osddrain: Make sure the OSD will be set to available if errors during drain...

osddrain: Make sure the OSD will be set to available if errors during drain occur. Added switch for debug output and OSD shutdown.


git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2619 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534