I think this documentation is a little misleading as it doesn't seem to be an accurate reflection of the current capabilities of the framework, more an exposition of where we hope it might go in the future.  In particular, I'm hung up on the idea that services must specify dependencies on implementations (ie, the `jetty-service`) and not an interface.

In fact, maybe all of this should just go into the 'hopes and dreams' section, since I don't think trapperkeeper currently supports any of it ... right?  Mainly, that there is no way to define a contract of a service separate from its implementation, or to say that two services implement the same contract.