Pinch to enable expanded desktop

Change-Id: I8ea87b6eac8131c597d77089b754002da3ead444

Conflicts:
	res/values/strings.xml
	res/xml/preferences.xml
	src/com/android/launcher2/preference/Preferences.java
	src/com/android/launcher2/preference/PreferencesProvider.java
	src/com/cyanogenmod/trebuchet/Workspace.java