Add option to set the color of the digital clock widget

PS2: fix update bug

Change-Id: I2fb472e00d853fed55baae4b36cdc88caf338630
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>

Conflicts:

	res/xml/settings.xml
	src/com/android/deskclock/SettingsActivity.java