Feature/permission request on start

[lagerspetz]

Permission request to block user from using Carat before all necessary permissions are granted.
@jhamberg can you check if this works on a new user's device properly? My Huawei is currently testing a proper fix to #61 .

[lagerspetz]

This is missing the permissions rationales still:
https://developers.google.com/android/guides/permissions

[jhamberg]

With your changes the application keeps prompting the Location and Telephony permissions. If you hide these with "Don't show again" then the following "Ignore Battery Optimizations" dialog will not work and instead force closes the application regardless of the choice clicked. Revoking permissions after they have been given also leads to a crash.

Doing a clean run (that is, accepting everything) seems to work fine.

[lagerspetz]

I want to in effect force these permissions to be accepted. READ_PHONE is used for UUID to make carat id collisions less likely, and location is used for moved distance calculation, so these should always be available.

[jhamberg]

I agree, those permissions are definitely needed (cannot trust SecureRandom to be implemented properly on all versions of Android). Perhaps we could initially request all permissions and then check for shouldShowRequestPermissionRationale on the callback which should return false if the user has hidden the prompt. If so, we can show a dialog taking them to the settings menu.