CBD-87: cbbackup, unit tests helper mixins
CBD-87: cbbackup, unit tests helper mixins

Change-Id: I8868c08b411fb13b20e5bc540d9a33f64713643e
Reviewed-on: http://review.couchbase.org/16607
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>
Reviewed-by: Ronnie Sun <06648be64f8fbc529d817d157ec32d385ea42f22@couchbase.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

couchbase/couchbase-cli,couchbaselabs/couchbase-cli,couchbase/couchbase-cli,membase/membase-cli,couchbaselabs/couchbase-cli,membase/membase-cli,membase/membase-cli,couchbaselabs/couchbase-cli