Support for Cucumber 4+ message format

[jmoglesby]

Cucumber 4+ has a default output format called messages.

While I've been able to use the stand-alone json formatter to convert messages into json for use with report_builder, it would be nice if report_builder supported the new native messages format.

Support for direct use of the messages format would be beneficial because:

1. I wouldn't have to maintain yet another library (cucumber-json-formatter) in my test environments
2. I could remove the extra processing step of converting from messages > json in my test scripts -- any time saved in large regression runs is a worthwhile thing

Thank you!

[ChrisVereb]

Agreed! There's a bugs in the standalone json formatter that is preventing it from processing our results in 5.x and we've lost our reporting as a result. While forking or updating this project to support the new message format may be a large effort, it's something cucumber is definitely standardizing on going forward.
A stopgap for many may be the integration of the standalone tool execution step into the report builder. It would at least keep the project still technically compatible with the two most recent major versions of Cucumber.