GitLab

Changes:
 -Use updated versions of ImageWorker & ImageCache from I/O 2012 app
 -Use copied DiskLruCache from system (rather than custom)
 -Use copied AsyncTask from system (to keep behavior consistent)
 -Ensure no strict mode violations or lint errors
 -Other misc bug fixes
 -Move single-use static methods in Utils to corresponding class

Change-Id: If21e045db1e1a80391169f3c9c9258d48345ab6b