Fix show observation points with the screen off

Issue #842.

Fixes screen off case, and the case where the map activity has not been shown yet in the app's lifetime.

This code (the previous PR) was written with the intention that the map activity is the main activity -which will be the case soon- but it complicated this hookup. I can simplify things a bit when we refactor out the current main activity.
Only change I'd suggest is to use `mPointsMissedByMapActivity`, `mCollectionPoints,` and `mCollectionPoints` as FIFO queues using the LinkedLink push() and pop().