Ruby upgrade

* Upgrades to new RVM way of setting ruby and gemset
* Upgrades to Ruby 2.1.2
* Upgrades Airbrake, i18n and Shotgun to latest within same major version to try to prevent breakages
* Change from debugger to bye bug
* ~~.powrc to .powenv~~

I think that’s the major changes. I’ve been using this in development without issue.