tests: Fix volume-status test script

* The functions now return the aggregated return value instead of just echoing it.
* Fixed the shd test loop to use the proper variable
* Added 'wait's for nfs and shd services to come online.

BUG: 764966
Change-Id: Iedbb5be0d5e50108ed4847d58625ccb093c22251
Original-author: Kaushal M <kaushal@redhat.com>
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/4856
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>