CMUpdater: use different notification icon when download fails

Use case:
1. User starts downloading update and puts phone away
2. After some time, user looks at the phone and sees CMUpdater icon.
3. User pulls the notification shade expecting the update ready to be installed.
4. CRAP, IT FAILED!

This patch changes "failed" notification icon to a default warning icon, so user
will know that something went wrong. Prevents frustration from incomplete updates.

Change-Id: I6896497eccb9539d649291310b68b6acb7169219
Automatic translation import

Change-Id: Ie931afde56fd1b82403b4b1c36cf69ab4d261033
Merge remote-tracking branch 'github/cm-11.0' into HEAD