Responsive design and some other tweaks

Hey folks,

It has been quite a while since I forked the project. Finally putting through a pull request.

Here's a rough outline of changes:

* remove mobile (like #17)
* add a responsive design
* other minor, and less minor tweaks, e.g. changing how the Twitter and RSS feeds work

I've developed in Chrome, whilst keeping an eye on things with a (non-mini) iPad and iPhone 4S & 5. Before opening this pull request I looked through the app on the latest Firefox on Mac and Windows, and IE8+. Things are working fine, however IE8 needs attending to. The site is still usable in IE8, but it's getting the mobile version and some parts aren't functional. In IE9 I was experiencing a JS error that appears to be related to autocomplete.

Recently I've had trouble scraping, so with that and with my smaller understanding of the entire site, I wouldn't be surprised if there are some screens or components that I've missed out on.

Another piece of testing I haven't done is front-end performance. Is there a staging app that we could run some webpagetest.org tests on?

There are some parts of the site that I think need attending to, such as the application show page. I would liked to have spent more time on this page, but I just wanted it to work and get deployed. Its mobile version needs attention, especially taking into account the different reasons a person on a phone might be using the site. The larger screen sizes should have their applications#show design improved too. There are some issues with the columns and it just looks a bit messy IMO.

I'd also like to see views/applications/address.html.haml looked at. When a user has had a successful search, the search form is still always first on the page. This is less of an issue on large screens, but when you're on a mobile device I expect the user to have a moment or 2 wondering whether what they did worked. This view's conditionals make it a bit tricky to organise things right. Maybe we need to look at redirects or just spend some time reorganising. Maybe there's a chance this user flow needs some love anyway?

I've been merging in upstream over time, so this pull request should merge smoothly.

Looking forward to hearing from y'all! Sorry about the length of time this has taken. It has been a culmination of things - work, play, other projects - that have caused this to take so long.

Apologies if I have forgotten anything in this description. Work is back on now, so I'll be busy for the foreseeable future, but I will still find time to help on this project.