fixed few issues found while testing gridftp plugin and file observer; made observer more generic by shifting some functionality to agent

    release 0.6 from tag 20151106

refactored utilities; use classes from common area wherever possible; added web service notification when experiment users get notified

added DB and DS web service interfaces for deleting user experiment role; added new delete-user-experiment-role command

introduced interface for notifying ds service to update experiment users; fix bug in linux experiment utility