Use shouldShowRequestPermissionRationale on Android for permissions

[tafelnl]

The helper hasPermission in Plugin.java just returns true or false. But more values are possible.

Namely:
1 never asked
2 denied, but not forever (android)
3 denied forever (user has to go to settings)
4 granted

The second possibility can be checked on android by calling shouldShowRequestPermissionRationale. The first possibility could be checked by putting the already requested permission to a storage for example.