Extract `Keywords` class.

Trying to fix the build for differences in sort order between ruby versions.

Allows us somewhere to hang additional behaviour over and above what we get from
a Gherkin language.
StepDefs.json...
Extract `Ast::StepResult`

BREAKING CHANGE

Formatter API changed for `before_step_result` and `after_step_result`, now
expects an Ast::StepResult.
Use dynamic CodeClimate badge
Turn off stepdefs.json

Too annoying.
Merge pull request #454 from chrismdp/include-ruby-version-patch-level

Include the ruby version patchlevel
Convert scenario outlines feature from legacy

Also take the opportunity to add better documentation to the feature
preamble (mostly lifted from the wiki)
Move showing differences to new feature folder
Removed redundant feature

I'm not convinced this feature is really necessary. It's not clearly
documenting anything, and the test itself is pretty useless.
Moved language help to new features

Took the opportunity to make the preamble clearer.