CBQE-0: added rest api support for modify remote cluster

Change-Id: I869c55609f1c7446ed79cec7da07814cb3659a72
Reviewed-on: http://review.couchbase.org/32302
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>