Adds stage overview stats to top of homepage. Links stage description pa...

- Adds stage overview stats to top of homepage (not live numbers yet -- couldn't get the Jekyll worked out to get it to read counts of instances of values in our project file)
- Links stage description page to homepage. This is pretty basic still in this iteration -- just a static link in the intro paragraph.
- Inserts text from gov.uk into status description page for attribution.

Screenshot:
![screenshot 2014-10-14 17 21 45](https://cloud.githubusercontent.com/assets/4827522/4638864/b34e8f06-5401-11e4-8208-8f0d4ea5969d.png)