[AndyB] Disable push notifications prompt 1.0

Features:

All phrases start with disablepushnotificationsprompt_ for your convenience.

Database changes:

This add-on will add a field called 'andy_disable_push_notifications_prompt' to your xf_user table.

Questions and answers:

Q: Why is this add-on useful?
A: If you preferr to not use push notifications and also clear your cookies often, then this add-on will prevent you from having to constantly disable the push notification prompt. The add-on fixes the "Never ask again" option by storing your selection in the account preferences.