Follow up patch to #1338 PR
Removes special testing variable in LocationChangeSensor, and adds an
additional test for when the location has not changed enough.
Merge pull request #1344 from garvankeeley/1338-sensortests-followup

Follow up patch to #1338 PR
Merge branch 'dev' of https://github.com/garvankeeley/MozStumbler into port-changes-from-fennec