CBQE-1902: implement get_recovery_task get_recovery_progress

Change-Id: Id75e698b0b6c6be82e44cfe893bb13a2353d43d9
Reviewed-on: http://review.couchbase.org/33241
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>