Added build date (ro.build.date from build.prop) to device info.

Change-Id: I5e19ee04de5c26822e171d4af8f4bfc052be9b74
Signed-off-by: Kristofer Ard <kristoferard@gmail.com>

Conflicts:
	res/values/strings.xml
	res/xml/device_info_settings.xml
	src/com/android/settings/DeviceInfoSettings.java