Adding definitions to processes and tests
Reworking the process definition system

Process definition is crucial at this point, and the way I had it before
was more of a hinderance than a help, so I've looked at it again and now
you can define these in a self contained bootstrap file. You don't pass
the instance of the process anymore, rather the name of its service so
it all still runs through the DI, which means they can be mocked and
tested properly. Although the tests for skeleton command need some more
updates now!