Rename site to "The OpenPolitics Network"

This is just an idea to let people try the rename I suggested in #56 on for size. I've just changed the main title, and removed the paragraph that talks about not being a party yet but aiming to have candidates, as it was a little outdated. I've explicitly *not* stated that we *are* a party called the OpenPolitics Network, that's undecided as yet.

![screen shot 2014-07-21 at 21 12 51](https://cloud.githubusercontent.com/assets/3565/3649560/81a5ef98-1113-11e4-8a2d-0c346a4f54bc.png)