CBQE-1561: add tests for system catalog

Change-Id: I20df9e33dc1f6437303b32b439bd8c6ee7f69ace
Reviewed-on: http://review.couchbase.org/38095
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: buildbot <build@couchbase.com>