CBQE-0: implement print_UI_logs in rest_client

Change-Id: Ie50465f3fbcb8631eba77c59a1b0f8df005f8daa
Reviewed-on: http://review.couchbase.org/33249
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>