handle requestPermissions on sdk 23 and later
On first run, permissions for vpn aren't asked yet.
Caused by: java.lang.IllegalStateException: Activity {se.leap.bitmaskclient/se.leap.bitmaskclient.eip.VoidVpnLauncher} did not call finish() prior to onResume() completing
The reasoning is hiding in here: https://plus.google.com/+DianneHackborn/posts/LjnRzJKWPGW https://commonsware.com/blog/2015/11/02/psa-android-6p0-theme.nodisplay-regression.html
(from redmine: created on 2016-10-13, closed on 2016-10-13)