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.
In a sense yes.

Here's the situation currently:

- If I install the Android 4.4.2 SDK Platform, that will be preserved after a Homebrew upgrade.
- If I install the Android Support Repository, that will be preserved after a Homebrew upgrade.
- If I install the SDK Platform tools, they will be lost on an upgrade. (They are installed to the cellar)
- If I install the SDK Build tools, they will be lost on an upgrade. (They are installed to the cellar)