Create the R.java for aar libs

Ok this commit is not very clean but it works...
We should seriously refactor a lot of stuff down there and use the AndroidBuilder from the builder lib.

I copied some stuff from AndroidBuilder and changed it a bit to make it work in our project.


This pull request make it possible to create the R.java for every AAR dependency by using the R.txt

Edit:
I have tested this myself in a real project using an aar without any classes and it worked :)

Currently this cannot be tested using the sample aar-actionbarsherlock project as the consumption of the classes.jar does not work