* Remove @EnableDiscoveryClient and @EnableEurekaClient as there are now optional.  Fixes #2241.

Signed-off-by: Gregor Zurowski <gregor@zurowski.org>

In addition to `eureka.instance.hostname` property you can now defined `sidecar.hostname` in order to set different hostname from application and its sidecar.
However if `eureka.instance.hostname` is present it will override `sidecar.hostname`.

Fixes #981

Fixes gh-1205

See gh-896

fixes gh-847

Allows for more fine-grained configuration of what to ignore.

If the management.port is explicitly set to something other than the
server.port, we can use it to set the status page and health URL
default values. (They can still be overridden by config properties.)

If management.port=0 there's not much we can do because we don't know
the port number yet when the instance config is created.

Fixes gh-425

Implements forwarding of eureka CacheRefreshedEvent as HeartbeatEvent,
rather thank serialization hack.  Uses new Eureka DI functionality
(mostly there, some issues). Updates EurekaJacksonCodec to be
"DataCenterAware". Reference EurekaClient interface rather than
DiscoveryClient class.

fixes gh-349

Added a LocalApplicationHealthCheckHandler that checks the local app and sends the appropriate status to eureka.

fixes gh-251

fixes gh-225

update sidecare enabled property, make eureka portion of config conditional on eureka on classpath so other DiscoveryClient impls can use it.

fixes gh-98

Handle InstanceRegisteredEvent and RefreshScopeRefreshedEvent in ZuulHandlerMapping rather than ProxyRouteLocator.
Move /routes endpoint out of ZuulHandlerMapping into RoutesEndpoint (because of a problem when I added @RefreshScope to ZuulHandlerMapping)

removed classes now in spring-cloud-commons

Fire InstanceRegisterEvent after eureka registration, then components can listen for that event and safely access DiscoveryClient.

updated sidecar so the health and info urls go to sidecar, but homepage and non-secure-port go to local app