Refactor event broker to use an injectable service locator (ugh) #6
Description
So... having learnt from Nimbus, we don't want people to supply their own event brokers - or ourselves to have to supply multiple event brokers for different containers etc. that we then have to test.
If we have our own single event broker that takes a dependency on a Func<IEnumerable<IHandle>> or similar then we can unit- rather than integration-test it and retain control of behaviour.