Add updateCount and clear data after send

Nice package and upon using the package I would like to make 2 updates:

1. Implement StatsdDataFactoryInterface::updateCount liuggio/statsd-php-client from v1.0.12 (latest stable).
2. Clear data after current data being sent (flush and clear buffer), so clients can call send on-demand in additional to app shutdown, useful for long running background process.