[WIP] Support Cucumber 2.0

[olleolleolle]

In order to get the specs to run against Cucumber 2.0, this change requires files from the new cucumber-core gem.

Next steps: to see whether the formatter works as intended. This change makes the specs run green.

• see "cannot load such file -- cucumber/ast/scenario" error is getting when i tried to use pretty face gem in my profiles 'default: FIG_NEWTON_FILE=default.yml --format PrettyFace::Formatter::Html --out results/index.html browser=firefox' #39
• pass Spec specs
• pass Cucumber specs
• fully use Cucumber 2.0 API
• be able to create an HTML report on a simple Feature file (is there one for general testing use?)

[olleolleolle]

This PR will be beefed-up and when ready, presented again.