Add callback for "Widgets" button click in launcher

Bug: 12553852
Change-Id: I8befd046242b32e86dbc6c98e6d97f0307380dd0
update placeholder on package install or restore

Bug: 10778992
Change-Id: I3293d8bab8ae0ef49fc5554531bba5bd6f70932c
use restored icon for restored app shortcuts

Bug: 10778992
Change-Id: Ie430a6587d49dc0d78b87b81582c0cef7c281017
Fix issue where clings didn't appear after set up wizard (issue 13077829)

-> Also removed the db-created as a criteria for showing the clings
   (this was a bit problematic in some cases and going forward)
-> Instead, we use database upgrade as a signal to not show the clings.
   This is used instead of the above criteria (to prevent old users from
   seeing the migration cling and losing their data.)
-> Stripped some old code related to custom clings that's no longer used.

Change-Id: Ib5e5285e5ddbc60e69eb998ee9fd092ae879150d