Adding halo-enable option Summary: - Master option for halo geo-replication - Added prove test for halo mode - Updated options do values which should work "out of the box" for most use-cases, just run "enable" halo mode and you are done, the options can be tweaked as needed from there. Test Plan: - Enabled option, verified halo works, disabled option verified async behavior is disabled - Ran "prove -v tests/basic/halo.t" -> https://phabricator.fb.com/P12074204 Reviewers: jackl, dph, cjh Reviewed By: cjh Subscribers: meyering Differential Revision: https://phabricator.fb.com/D1386675 Tasks: 4117827 Conflicts: xlators/cluster/afr/src/afr-self-heal-common.c xlators/cluster/afr/src/afr.h Change-Id: Ib704528d438c3a42150e30974eb6bb01d9e795ae Signed-off-by: Kevin Vigor <kvigor> Reviewed-on: http://review.gluster.org/16172 NetBSD-regression: NetBSD Build System <jenkins.org> Smoke: Gluster Build System <jenkins.org> Reviewed-by: Shreyas Siravara <sshreyas> CentOS-regression: Gluster Build System <jenkins.org>