Add support for rspec3

There was several issues :

- ``with_around_each_hooks`` is renamed to ``with_around_example_hooks`` in rspec 3.0
- ``@example`` does not exist anymore in ``__run_next_step__`` This issue was present in rspec 2.99 as well , it made all specs pass even if they should not. Instead, I clean the steps and re-raise the exception that is later caught by rspec himself. Not sure about that exactly, but I tested with rspec 2.14 and everything seems fine so backwards compatibility seems to be in the party.

Cheers


Could you get all the whitespace changes out of this commit? Formatting changes should be separated from functional changes or it becomes very hard to read the history.