Add new software features

Wearable devices are much more stripped down than
handheld and tablet devices. There are system
services that must not be present on wearable
devices. Those services have their own feature
xml files that get copied to the system image
as needed. They are included by default in the
handheld and tablet core feature files in order
to maintain previous behavior.

Wearable devices should always copy the
data/etc/wearable_core_hardware.xml file and
whatever other files that represent required
services (eg. data/etc/android.software.print.xml).

Change-Id: I410442d45854fe54cba1131ce488a5a459ac580a