Fixed the Collaborator when it is a ObjectProphecy.

This came up when updating specs for prophecy which mocks ObjectProphecy. It was actually calling the method on the ObjectProphecy instead of returning a MethodProphecy.
Added interfaces for totaling examples from events.

This will make it easier to show progress in formatters.
Fixed unwrapper for arguments implementing the WrapperInterface.

Wrapped object is already revealed.
Merge pull request #116 from jakzal/collaborator-fix

Fixed the Collaborator and Unwrapper
Merge pull request #118 from whatthejeff/suite-count

Added interfaces for totaling examples from events.