Refactor of the feature step, reporting and fix for the multiline background steps.

Based on the #79 and #80. There was some refactoring needed to preserve the reporting functionality.
Also removed other entry points for the "generation", "cucumber_json" and "reporting" so now it shows "bdd" on the start only once for the plugin.
It's a matter of taste, but my reasoning is: consistency between json, html, python and others. Docstrings use triple doublequote, not single. Double quotes allow using apostrophes without escaping. I just like it more recently