Add <feature-group> tag and change aapt badging

A <feature-group> represents a set of features required
for an app to be compatible with a device. Multiple
<feature-group> elements represent a logical 'or'
of required features.

Features defined in the old way with <uses-feature> tags
under the <manifest> tag are automatically added to each
feature-group defined.

Defining a <feature-group> means that any default
features are not included (such as android.hardware.touchscreen)
and declared permissions do not imply any features.

Change-Id: I45626f0fdc546e47bcf2aead7ef05ebcca12b023