HTML output format feature

[ChrisDryden]

I am using cucumber currently for a work integration test suite and it is replacing a test suite that previously had the ability to generate an html file with a summary of the integration test suite. I will be working on adding this functionality to this library and tracking the progress here.

[MarcoFuykschot]

i already done some work in this area as a separate crate https://crates.io/crates/cucumber-reporter