Allow Emergency Alerting to be disable via Data Package

[CoryFoy]

Is your feature request related to a problem? Please describe.
Similar to issue #46 agencies deploying TAK Tracker may not want the emergency alerting to be available for an end-user.

Describe the solution you'd like
Allow a setting in the .pref file to disable

Additional context
We would need a way of "resetting" the option if a user changes data packages, or perhaps a way to "clear" a connection that also resets the prefs