object-store: Added busy_wait unit test to Glusterfs.py

Change-Id: Ifee5dccd47a3e301812533851c45b9fe853f9b71
Signed-off-by: Luis Pabon <lpabon@redhat.com>
Reviewed-on: http://review.gluster.org/4983
Reviewed-by: Peter Portante <pportant@redhat.com>
Tested-by: Peter Portante <pportant@redhat.com>