Syntax highlighting for examples

[timofurrer]

Add syntax highlighting for the examples on http://radish-bdd.io

[goodwillcoding]

@deeechun ... there is a library called highlight.js .. it has syntax highlighting for python and gherkin.
I suggest that unless @timofurrer wants more "html-y" solution

links: https://highlightjs.org/
demo: https://highlightjs.org/static/demo/

[timofurrer]

@deeechun @goodwillcoding I actually had highlight.js in mind. Sorry for not mentioning it earlier.

[timofurrer]

See #5