CBQE-1257: tests hang on RestConnection creation in tasks

Change-Id: I873aa37c7c119750ec68e6f3c54e492436b1519f
Reviewed-on: http://review.couchbase.org/25959
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: buildbot <build@couchbase.com>