Cleans stages and project pages

- Minor text edits to stages intro text (including GOV.uk --> GOV.UK)(it seems like this is what they use on their site)
- Gave a bit more space to stages text and weighted intro line
- Moved stages page 'back' link to the top of page to match style on projects pages
- Cleaned HTML on projects pages (in particular removed unused css_id jekyll statements)
- Simplified and cleaned projects page layout, a la below:

![screenshot 2014-10-23 15 31 54](https://cloud.githubusercontent.com/assets/4827522/4762650/d4fbb9a8-5b04-11e4-94ce-c2f1c1b55d6e.png)