Work in progress: import autorestart into dogstatsd

Move AgentSupervisor to Daemon.
Plus a number of other pylint fixes.
Merge branch 'master' into dogstatsd-autorestart
Allow MySQL check configuration via a mysql config file

For more complex configuration (e.g. specifying SSL certificates) it's
useful to use a mysql.cnf instead of specifying flags by hand.
Merge branch 'master' into dogstatsd-autorestart
Initial tests for autorestart
Merge branch 'master' into dogstatsd-autorestart
Better name for `to float` method.
Clean up unix system check code.
Remove bare except handlers in system/unix
Refactor disk check into understandable code.
Optionally filter devices from disk stats.
Run disk parsing checks on every os.
Don't filter by default in disk test harness.
Only run disk collection on the unix platform.
Make the parse df function fit on a screen.
Filter devices from iostats.
Adding missing re import to config.
Adding configuration example for device limiting regex.
Consolidate network metrics submission code.

This will make it much easier to filter device names.
Show checks.d syntax errors in info cmd.