Bump op-version for 3.7.0

Change-Id: I4542edeca140bc2252d765b5cfc2e24d1d90cdb1
BUG: 1122398
Reviewed-on: http://review.gluster.org/8354
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>