Better programmatic configuration.

- Dispatcher servlets and their contexts are now easier to configure.

- Moved all resources to test directories to better reflect real-world use cases.

- Added tests that start up Jetty and used retrofit to make a sequence of API calls.

- Fixed bug in rhizome utils that was causing unhappiness when a configuration was not found.

- Fixed bug in rhizome configuration service that was prevent configurations from being properly updated.

- Added toString method for simple configuration key.

- Added JacksonConverter based on square retrofit converter, but with some additional handling for null bodies.
It just handles the dependency graph for getting the Jetty configuration and creating the configured Jetty object once the configuration beans are ready. This can probably be done statically or on sprout().