Refresh dashboard category data when package changes.

Category needs to refresh when package information changes. So
CategoryUpdateTask should not early exit by just checking config
changes.

This is needed to refresh UI when user enables activity such as
developement options.

Also made CategoryManager thread safe because it's called in both UI
thread and asynctasks

Bug: 31781480
Test: manual

Change-Id: Idcdcd39f727aba423350f3874af5612474e24e28