MB-19339: Automatically create an entry for "default"
MB-19339: Automatically create an entry for "default"

In order to support backwards compatibility with the default
bucket concept we need to have an RBAC entry which represents
the default bucket. Until ns_server provides the correct
definition for this entry we'll just automatically create
an enty so that the rest of the system behaves as expected.

Change-Id: Ic28e29d7a02093b866d637b1db7ee793c9a765db
Reviewed-on: http://review.couchbase.org/73428
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

daverigby/memcached,daverigby/memcached,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,couchbase/memcached,daverigby/memcached,couchbase/memcached,daverigby/kv_engine,couchbase/memcached,daverigby/memcached,couchbase/memcached