Implement new Granular Permissions

[tasomaniac]

More info: https://developer.android.com/preview/features/runtime-permissions.html

We need to check if the permission is given in all requests.

[Splaktar]

There does not appear to be a great need to merge something like this soon. It can and should be tested, but doesn't need to be completed in the near term.

"If you install an app using the new permissions model on a device that is not running the M Preview, the system treats it the same as any other app: the system asks the user to grant all declared permissions at install time.

Note: For the preview release, you must set the minimum SDK version to the M Preview SDK to compile with the preview SDK. This means you will not be able to test such apps on older platforms during the developer preview."

[friedger]

The user can revoke the location permission.

It looks like we deal with this already gracefully.

[friedger]

For M we need to request the location permission.

[tasomaniac]

Although we seem that we request a lot of permissions actually we don't. We only have 2 dangerous permissions: Location and GET_ACCOUNTS.

Accounts will be removed thanks to new Auth lib from Google. #616 After that, we should handle location permission and we will be done.