Bug 1014338 - Pre: add ThreadUtils.assertNotOnUiThread. r=margaret
Bug 1014338 - Part 0: move Distribution class into its own package. r=margaret

--HG--
rename : mobile/android/base/Distribution.java => mobile/android/base/distribution/Distribution.java
Bug 1014338 - Part 1: rework distribution handling. r=margaret

This patch cleans up some of the distribution loading code, and provides a hook
point for callers to hang code that needs to run once the distribution has been
loaded.
Bug 1014338 - Part 2: add delayed distro initialization hook. r=margaret