More specific error messages

[xbony2]

For example, if an English file isn't found (which is apparently occasionally possible):

Traceback (most recent call last):
	3: from run.rb:1:in `<main>'
	2: from run.rb:1:in `require_relative'
	1: from /Users/xbony2/git/ATT-9001/lib/att9001/att9001.rb:55:in `<top (required)>'
/Users/xbony2/git/ATT-9001/lib/att9001/att9001.rb:55:in `read': No such file or directory @ rb_sysopen - resources/PR/en_us.json (Errno::ENOENT)