Update the documentation to use the new expectation syntax.

* Update cukes to use the new expectation syntax where possible.
* Update RDoc documentation to use the `expect` syntax where applicable.
* Add RDoc documentation for `syntax=` & `syntax` methods.
* Rename cukes to reflect new syntax.
Merge pull request #497 from tundal45/move_to_expectation_syntax_in_docs_cukes_and_readmes

Update documentation to use the new expectation syntax.