android-sdk: Certain files are lost on upgrade

Currently, the android-sdk will install the platform-tools and build-tools into 2 directories that should be outside of the android-sdk cellar, but are not.

Because of this, on an upgrade of the android-sdk, any installations of the platform-tools and build-tools will be lost.

The attached patch fixes this by adding the two additional directories to the existing list of preserved data directories.
Yeah. The whole program is basically a package manager.

With whatever lines are checked or unchecked, you can hit the install or delete buttons to do the requested action.

It might make some sense to clear out these folders if no android-sdk installations remain, but I'm not sure how we would want to go about implementing that.

![untitled 2](https://cloud.githubusercontent.com/assets/116754/3413199/fc3f2d00-fe08-11e3-97b3-6ce1813dc1ae.png)