Validate the conn input parameter
Validate the conn input parameter

Change-Id: I99d3a217fadca532caa2e8dbe14340a357b2857f
Reviewed-on: http://review.couchbase.org/53651
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

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