working pluggable formatter
Merge branch 'master' into pluggable_formatter

* master:
  really fix utf-8 encoding comment.
  more utf8 encoding comments.
  configure travis-ci rake task
  relax metrics settings.
  Mostly syntax and style fixes.
  added utf8 comment
  rubocop autocorrect
  use devtools gem for metrics

Conflicts:
	lib/active_model/error_collecting/emulation.rb
	lib/active_model/error_collecting/human_message_formatter.rb
	spec/lib/active_model/error_collecting_spec.rb
Merge pull request #6 from aq1018/pluggable_formatter

Going to merge this in for now, since it doesn't change any existing behavior.