Informative failure for missing files mapped in universal#83

Merged

jsuereth merged 2 commits intosbt:masterfrom gmjabs:master

Nov 25, 2013

Commits on Nov 21, 2013

Error out with a useful message if a mapped file in unversal doesn't exist.
gregj
committed

Commits on Nov 22, 2013

Verify mapped files exist in settings for all configs.
gregj
committed