* 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

changed constructor visibility from private to protected in order to be able to derive from Application

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.

* Separate AppStore from AppRegistry
* Allow Id generation to be altered
* Remove logic from Application; Move id genretation into AppRegistry
* Make AppStore threadSafe

* registry-key is derived from URL
* option to specify a management-URL and other various config options see spring-boot-starter-admin-client/README.md
* less chatty registration
* some more test cases
* show application URL in overview and headline
* show application info in overview
* set HTTP-Codes in RegistryController

fixes #13
fixes #16
closes #17
closes #18

I didn't add the key-value-properties to the Application. Since it was somehow redundant to the /info-endpoint.