Add a setting for Shutter Speed

Change-Id: Ieebe50a4be04e7fea9301da63c008e36f4ec0dbd

Conflicts:
	res/values/cm_arrays.xml
	res/values/cm_strings.xml
	res/values/config.xml
	res/xml/camera_preferences.xml
	src/com/android/camera/CameraSettings.java