Update to Spring Cloud Brixton and add the concept of ServiceInstanceConverters.
A ServiceConverter is used to convert discovered ServiceInstances to
Applications. The old converter and one for Eureka is provided. It is also
possible to provide your own implementation.

closes #154

 * Use @EventListener instead of ApplicationListener-interface
 * Don't inherit ClientApplicationEvent from ApplicationEvent - so JournaledEvent isn't needed anymore
 * added eclipse formatter rules
 * reformatted all files

Added a simple event journal, jorunaling all ClientApplicationEvents using a simple, non-persistent store. So all information is lost after restart. Added corresponding view to UI.

The health-check is made at a fixed interval (default: 10s) for all expired status-information (default-lifetime: 30s).
The application health-endpoint must either respond with a JSON-Body having a status-field or with an empty body and all 2xx-http-responses are interpreted as UP and every other status as DOWN.

To enable, you just have to add a DiscoveryClient to your Spring Boot Admin Server.
Also did some code polish.
Closes #44