Update documentation on main page

[sergeytrasko]

For some time already the project is evolved from 'cukes-rest' to 'cukes'. It's not about only REST now, it's bigger.

So the documentation on main page (readme.md) should be aligned accordingly.

[berndgoetz]

Yes, that makes sense. Plus I'd like to see a documentation or a pointer to a class that contains all Cukes properties descriptions, such as a description of all possible values for cukes.logging.http.responses.include.