features/changelog: Crash consistency of changelog wrt snapshot

This patch introduces call-path fop details logging for data operations
in CHANGELOG.SNAP. This feature is enabled with barrier-enable
notification and disabled with barrier-disable notification.

Change-Id: Ib548d34203eb99cea478a6baff402e82251c73a4
BUG: 1128093
Signed-off-by: Ajeet Jha <ajha@redhat.com>
Reviewed-on: http://review.gluster.org/8533
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>