MozStumbler v0.20.4
Merge pull request #609 from garvankeeley/0.20.4

Release 0.20.4
Remove old preferences keys on upgrade
Merge pull request #611 from illarionov/removeOldPrefsKeys

Remove old preferences keys on upgrade
Determine whether the cell location is updated when the screen is off
Workaround for no Cell Location Updates When Display Off
https://code.google.com/p/android/issues/detail?id=10931

Conflicts:
	res/xml/preferences.xml
	src/org/mozilla/mozstumbler/cellscanner/CellScanner.java
	src/org/mozilla/mozstumbler/cellscanner/GeminiCellScanner.java
	src/org/mozilla/mozstumbler/preferences/Prefs.java