[WIP]Initial runtime permissions for android

[barryvdh]

Initial implementation for #110
Based on https://cordova.apache.org/docs/en/dev/guide/platforms/android/plugin.html

Done:

• Implement requestAlwaysAuthorization for Android 6
• Ask permission, return result in js callback

Current problems:

• request is not blocking, so the callbacks need to be used. But these are not working on all versions. I suggest that, when the function is not available (eg ios7), it always executes the success callback. This is a breaking change however.
• I only changed 2 examples to use the callback yet.
• Code style is messed up from switchting editors, but hope you get the idea :(
• Check on older Android? Always run success callback?

[barryvdh]

The correct way to handle this would be upgrading to Android SDK 0.10.x and using the new SystemRequirementsChecker (introduced in 0.9)