Merge pull request #7 from Goutte/master

Success tally for the runner, and dumbed-down README.
refactored to use worker library and run concurrently
more future hell
inlined futures
workers merged
Change worker dependency URI to public.
Big Merge BROKEN : Illegal argument on isolate message (object is a closure)
Big Merge OK.
- Less global vars
- dherkin_core does not depend on dart:io
- Cleanup
Cleanup.
Cleanup.
Merge remote-tracking branch 'upstream/master' into big_merge_clean

Conflicts:
	example/run.dart
	lib/dherkin.dart
	lib/src/gherkin_model.dart
	lib/src/gherkin_parser.dart
	lib/src/outputter.dart
	pubspec.yaml
Cleanup.