Android 6.x permission fix

[clemmyn23]

• Added permission check (and request) on startup
• updated Gradle scripts to Android API 23
• ContextCompat and ActivityCompact support libs used for backwards compatibility

It compiles and runs fine on my 5.1.1 phone. Haven't have time to set up a 6.x emulator yet so feel free to test it before merging (or wait for libgdx team to implement).

You will probably need to update your Android SDK for it to compile.

More info: http://developer.android.com/training/permissions/requesting.html http://developer.android.com/tools/support-library/index.html

[kbz]

If this works, It will be amazing, thanks.

I'll review this later this week.

[dgw]

/me pokes @kbz

If you want help testing, I do run a 6.x device.