Adjustments to timers for Passive Mode. Most important: GPSScanner, don't put time and distance restrictions on the listener, I get greater percentage of fused locations doing this (like 10x). AFTER getting a location, then do our own time and distance threshold checks.
* StumblerService now runs on a background thread. Intent message is now synchronous within the service.
* Passive mode uploading is completed, when the db is non-empty, start a timer to periodically check if the wifi is connected and the screen is on, if so do an upload. If the db data is too old, delete it.
Set the enabled state of the service based on the Firefox pref sent
Merge pull request #704 from garvankeeley/passive-upload

Fennec Integration: StumblerService to a thread