Allow adding widgets from user profiles.

The goal of this change is to enable support for appwidget from
user profiles to the user main profile. A user profile is a user
which is associated as a child of the main user profile. For example,
a user may have a personal (parent) and corporate (child) profile.
The device policy should be able to control whether adding a widget
from a child profile and given packages is allowed. This change
assumes that all packages from managed profiles are white listed.
Another change will add the device policy changes.

Change-Id: I267260b55d74c48b112a29979a9f59eef7a8194e