Re-inform user about closest AED after a while

[marians]

Status quo: When a user has opened the application and seen the information about the closest AED candidate, he/she never gets that information again. Only a forced reload would initiate this.

This is somewhat awkward when, for example, the user has opened the browser, then turned of the device screen, moved around in the city, then turned the device screen back on. In this situation, the closest AED alert should appear again.

Programmatically, this could be bound to two different conditions:

• Time since last alert. (E.g. at least 5 minutes)
• Distance moved since last alert (e.g. at least 500 meters)

Only one condition would have to be true.