Foreman and Nginx support added.

Application lifecycle is now managed by foreman and exported to upstart.
An optional nginx plugin is provided with site templating and service reloading.

* foreman and upstart integration in activator.rake (export/start/stop/restart)
* Procfile overridable template with extended configuration options
* foreman envfile support (with templating coming soon)
* rbenv support for executing rbenv sudo tasks using rvmsudo (rbenv support coming soon)
* better capistrano flow management (using release_path en update hooks)
* nginx plugin with site templating, site enabling and service reloading