Minimum viable Android M runtime permissions handling for H.

Minimum viable Android M runtime permissions handling for H.

Creates new activity for permissions handling: both checking
for permissions and handling error condition when critical
permissions are not present. The reason for creating a
new activity is so the app does not attempt to continue
executing OnCreate, OnResume etc, which opens
the camera while the dialogs are showing. This should
not slow the app down because the permissions activity
will only run when a) the first time the app has
insufficient permissions and b) when a critical
permission is missing and the app needs to shut down.

Bug: 21273463
Change-Id: I603acfb3057ba26b9cfa7935eb4cb24b5d547cb5