Fix issue #2643754: Launcher is caching widget layouts for too long

With the .apk file names now changing during an update, we need
to make sure to flush all caches related to a package when the
package is removed.  Otherwise we can continue to use the old
package, since its old file may still exist if we try to load it
too soon.

Change-Id: I15f08dffca3feac999dbca4f24bef12a30ca0a66