aapt start failed on my Mac.

Not sure if this library still under maintenance? Seems like the build tools version is very low.

I'm evaluating this library for our project recently. I setup the build tools according to the specified version,
- Tools/Android SDK Build-tools (Rev. 21.1.2)
- Android 5.1 (API 22)
- Extras/Android Support Library
- com.google.android.gms:play-services-location:10.0.0
- com.google.android.gms:play-services-places:9.2.0

But build failed with the following error:

```
* What went wrong:
Execution failed for task ':android:processDebugResources'.
> A problem occurred starting process 'command '/Users/chaofan.zhang/Library/Android/sdk/build-tools/21.1.2/aapt''
```

When I try to run `aapt` itself, it gives me `bad cpu type` error.
```
% /Users/chaofan.zhang/Library/Android/sdk/build-tools/21.1.2/aapt
zsh: bad CPU type in executable: /Users/chaofan.zhang/Library/Android/sdk/build-tools/21.1.2/aapt
```

Can you upgrade the android build tool version, sdk version, also gradle version?

I tried to update those build tool and sdk versions to current, but it introduce api changes, and need to udpate code.