Fix issue #2084148: Define the format for the auto focus preview for barcode scanning

Add new manifest/aapt support for specifying device features an application
requires.  The aapt badging now returns these (as well as uses-permission since
I need to look for those anyway); if an app doesn't explicitly request the
camera feature but does request the permission, then aapt will say that it has
requested both the basic camera feature as well as the autofocus feature.

Here's what you put in your manifest to say you need a camera but don't need
autofocus:

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />

Here's what will be seen from aapt:

uses-permission:'android.permission.CAMERA'
uses-feature:'android.hardware.camera'
uses-feature-not-required:'android.hardware.camera.autofocus'

Change-Id: I4dd19cee0486cc54771f5bf14fc9db0e892115d5