Launcher3 multi-profile support

Use LauncherApps API and badging APIs instead of PackageManager.
With compatability layer that uses PackageManager pre L.

Adds support to show apps from current user and any managed profiles.

Background: Managed profiles are user sandboxes that are visible from
the primary user and can be launched as if they are a part of this user.
A launcher should now be capable of listing apps from this user as well
as related profiles of this user.

Launching of activities is now via the LauncherApps interface, to allow
for cross-profile app launching. Only activities with category LAUNCHER
can be added as a shortcut on the workspace for a managed profile.

Widgets and non-application shortcuts are only supported for the
current profile. Widgets from the managed profile are not available.

Change-Id: I5f396b1bf7f91ad91a5710ea4a0fd14573972eb9