Add a system menu

This forms the top level menu for the 'system' category of configuration
items. It loads its submenus from a similarly named dir.
Add restart/start task methods

For when we want to restart an upstart task, which dont have instances
since they are not permanently running.
DatabaseOps should save configuration in AR::Base

So that we can save some config in the AR::Base, and all models can
query the base for common config options.

Also add tests.
Propagate :test_mode from Runner to App

So that App can set the AR::Base with the appropriate configuration
(which will be used by the models).