Add Procfile container

This includes:

1.  Refactoring common component code out into base_component.rb
2.  Installing the mozroots to `app/.config` at staging time (rather than runtime)
3.  Removal of the `setup_mono.sh` that had to be run at startup time
4.  The addition of the Procfile container, which enables multiple startup commands to be specified in a `Procfile` ala [ddollar/foreman](https://github.com/ddollar/foreman)