Revert "app: Fix CTRL+Q and ALT+A handling"

This reverts commit 01c0609bc3a291df67cd708f1c2bb3b30bfae04a.

https://bugzilla.gnome.org/show_bug.cgi?id=706415
app: Take default modifiers into account

When checking for particular modifier bit in a key event, we must take
into acount any default modifiers that might be set on the event's state:

https://developer.gnome.org/gtk3/stable/checklist-modifiers.html

This fixes CTRL+Q and ALT+A keyboard shortcuts not working anymore.

Thanks to David Kind and Paolo Borelli for pointing this out.

https://bugzilla.gnome.org/show_bug.cgi?id=706415