Easier development setup

Getting TextSecure to build out of the box wasn't immediately obvious, I added ActionBarSherlock as a submodule and tweaked the information from [this post][1].

After that,

```bash
git clean -xdff
./configure.sh
ant debug
```

results in a working APK.

Is hardcoding the first configured target in the android system poor practice? Should it be a param?

[1]: http://iheartryan.com/post/textsecure