Sass

A little bit whack, does the job though. I am not 100% confident this should be merged, see if you can get it working locally?

- Watcher seems to constantly rebuild once it sees a scss change, which is pita.
- CSS needs commiting, GitHub pages won't run Jekyll plugins, the .gitattributes I added hides the compiled CSS from diffs though, which is handy.

NB: I added a Gemfile (and Gemfile.lock) to keep track of gems required, you'll need to run `bundle install` (or shorthand, `bundle`) to get up to speed. You'll have to `gem install bundler` if you don't already have it. Think Composer, for Ruby.

@liamjay66