* Since the hystrix.stream incorrectly handles HEAD requests we had to change
   the detection for the hystrix-endpoint to a GET request.
   Issue https://github.com/Netflix/Hystrix/issues/1369

 * We need to improve Zuul's SimpleHostRoutingFilter and SendResponseFilter to
   close the underlying socket when an error occurs when writing the response.
   I hope that the code can be removen when my PR gets merged.
   Issue https://github.com/spring-cloud/spring-cloud-netflix/pull/1372

Fixes #290

Remove the activiti endpoint from the default set of proxified endpoints.
This aligns with the non present defaults for hystrix.

Since a HEAD request to the heapdump triggers a dump we need to test the
availability of the heapdump endppoint via OPTIONS-request.
To get this working we need to ensure that the OPTIONS-request are dispatched
to the zuul servlet as this wasn't done prio to this commit adding the
OptionsDispatchingZuulController.

Detecect endpoints by making a HEAD request instead of querying the configprops
since it is broken when having a second applicationContext

Adds an application view that displays a list of
Liquibase migrations as retrieved from the /liquibase Actuator
endpoint. The module is conditional on this endpoint being
available.

Adds an application view that displays a table of
Flyway migrations as retrieved from the /flyway Actuator
endpoint. The module is conditional on this endpoint being
available.

Fixes gh-206

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

Spring Cloud Brixton hasn't been released yet, so to get the Spring Boot Admin
release out. We downgrade to Spring Cloud Angel.SR3.

To not accidentally expose senstive urls only expose whitelisted
management-endpoints via the zuul proxy filter.

Deriving from Spring Clouds ProxyRouteLocator has become too difficult. It would
have required to either set fixed ZuulProperties or providing a DiscoveryClient.
So we are shipping our own lean version of it. Since the PreDecorationFilter is tightly
coupled to the ProxyRouteLocator we also have to use our own stripped down version.

closes #123

 * 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

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