Move to responsive site

This PR updates the Engine to work within the fronted repository. As rough summary of changes:

* Bump the Gem Version to 0.3.0
* Update to ruby 2.1.2
* Update to Rails 4.1
* Change Google Analytics Conversion tracking to Google Tag Manager (see similar [car cost tool commit](https://github.com/moneyadviceservice/car_cost_tool/commit/c85052672cceb89839002d001641ccab350140b3) for details)
* Remove CSS Namespace
* Adds appropriate category_id for each tool within the engine
* Add in page titles / description meta tags already in use on the existing live tools

It's still under 0, so minor patches are fine. However if this is going into frontend, may as well bump it to 1.0.0