XDCR -pause and resume framework (Aruna)

Change-Id: I9dc2e1c0667cc1bb22175816a9b012bd23017e5d
Reviewed-on: http://review.couchbase.org/33914
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>