CBQE-0: minor changes in rest_client.py

Change-Id: I5d3df856b06780d1d2a3c4fa46e9aa2c2cfcd386
Reviewed-on: http://review.couchbase.org/30262
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>