Implemented fixes and changes from code review

- Renamed stats.Start and stats.Stop to be clearer that they will be part of that package (when we do sub-packages).
- Made /status request actually succeed.
- Added final stats sending. Except... it doesn't quite succeed yet. The MeekConn seems to be already closed.
- Added WaitGroup to ensure stats.Stop doesn't return until the processStats goro has stopped. Also avoids possible panic due to settings allStats.stopSignal to nil before processStats uses it.
- Changes and comments to clear lint warnings.