engine:Gluster hook entity related entries

Added name and parents retrieval to entity functions
for gluster hook entity.
Added missing notitification entries for gluster hook
events.
Added entries for GlusterHookStage and GlusterHookStatus
enums

Change-Id: I1fd69508ccd882251540c27b14c855b42c39bec7
Signed-off-by: Sahina Bose <sabose@redhat.com>