Fixes for push notifications

This defaults webPushNotifications to false so that localdev won't get push notifications by default (still need local.json config to have static/config.json override tho)

This also allows deactivation of serviceworker which should prevent push notifications entirely instead of just not showing them in config. Still, maybe should make it more decent and not kill off serviceworker but just cancel the push and notify BE about it, but right now it's not used for anything else, so it doesn't really matter.

closes #235 (closed)