Add cucumber4 support fixes #90

[pmthexton]

This may not necessarily be the "correct" approach, in terms of the ability to support both cucumber 3 and cucumber >= 4

But given the lack of issues reported, I suspect most people who are using the plugin are perhaps still using cucumber3?

Also fixed some small bugs I ran in to along the way due to the unfortunately odd method I'm having to use right now for publishing results, as our existing automation runner executes feature files one by one.