Add the option for reload sql in runtime

[josejuanmontiel]

I think could be interesting use something like fsnotify to watch changes in sql file (when debugging or running outside the build... i need to try all the options) but the idea (later) is to have way to include new sql e.g. via API ... without restarting or in production...

[knadh]

Makes sense.

• A new --watch mode that auto-reloads.
• SIGHUP to send a reload signal to the app to reload everything.