MB-19339: Reset username cache as part of authentication
MB-19339: Reset username cache as part of authentication

Change-Id: Icf01a663a57aa143a1f98c2f7e7b8b1db7a74caf
Reviewed-on: http://review.couchbase.org/73564
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>

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