feat: Translated TOS/PP text!

* Pull translated TOS/PP text from repo, convert to HTML using grunt.
* Handle TOS/PP serving on the backend using new routes: `<locale>/legal/*`
* If `locale` is not specified or cannot be found, use a fallback template.
* Return 500 error with error message if a fallback template cannot be found.
* Front end requests localized TOS/PP partials from the backend, on demand, and inserts them into the DOM. partial vs full html rendering is determined by `Accepts` header.

Issue #634
refactor(build): Install the tos-pp repo using bower.

* Allows us to remove a bunch of extra code to manage the tos-pp repo.
* Add grunt-marked to npm-shrinkwrap.json.