Migrate to android studio

Alrighty, so after not too much fiddling around, I've managed to port the project over to Android Studio. I'm happy enough to can this if not everyone is in favour of it, but I do have it working.

### Pros
- No more eclipse
- Gradle builds
- App is way way easier to get set up with
- We can build the app on TravisCI (https://travis-ci.org/smap-consulting/sms-smap-gateway)
  - Can show travis CI build badge on the readme, giving us open source rep-points
  - more info on travis integration http://docs.travis-ci.com/user/languages/android/
- We can start writing tests and running them in CI
- No more fixing borked build paths as build path is configured in the `build.gradle`
- No more vendoring popular .jars
- We can start building .apks and uploading them wherever as build artifacts
- Android studio has a dark theme built in without having to install any whack plugins
- Its supposedly the future of android

### Cons
- Android Studio is still in Beta
- Everyone has to set up the project again
- I have only tested this on OSX so far, so not sure if it's fiddly on Windows / Linux
- New keyboard shortcuts to learn