geo-rep: Changelog History API changes

Additional argument added to API gf_history_changelog,
actual_end - The end time till where changelogs are available.

Added sort to history_get_changes API output.

BUG: 1091961
Change-Id: Id043409882a83cd0a7b9adc3d34d5147d17e532e
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/7747
Reviewed-by: ajeet jha <ajha@redhat.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Tested-by: Venky Shankar <vshankar@redhat.com>