Similar to @RibbonClient

fixes gh-288

https://github.com/Netflix/Hystrix/pull/921

Still a release candidate (not yet GA), but seems to work, so we'll
try and update before Spring Cloud is released again.

Fixes gh-546, fixes gh-567, fixes gh-553 (probably)

* feign-content-encoding-snapshot:
  Feign request/response gzip compression

fixes gh-561

Specifically CloudEurekaInstanceConfig where needed.

see gh-302

Other Ribbon clients in Spring Cloud use a ServerIntrospector
to check if the Server wanted to be secure. This change levels things
up (and makes the Spring Feign Client a lit easier to customize).

See gh-414

Most clients send "Transfer-Encoding: chunked" so this isn't often
an issue, but if they don't (e.g. if you use "-H Expect:" with
curl) then it's not a great idea to slurp it all into memory.

Fixes gh-563

When using Ribbon the hystrix config and metrics are namespaced
as "RibbonCommand" (via the group key). the command key can then be
serviceId, making it easier to remember how to configure
Ribbon and Hystrix.

Fixes gh-329

DRY

Allows ribbon load balancer implementations to answer questions like isSecure(Server).

Allows ribbon load balancer implementations to answer questions like isSecure(Server).

There are usually some hints available, especially if the Server
came from Eureka. Unfortunately Server on it's own doesn't contain
enough information (why?), but as a fallback we can guess that
anyone using port 443 is secure.

Fixes gh-459

fixes gh-417

Clicking running instances in eureka admin page

When click one of the up and running instances this should open the actual instance in separate tab

If the configserver registers with securePortEnabled=true we should
respect that in the discovery process.

Fixes gh-450

Change EurekaInstanceConfig.getSID to getInstanceId

fixes gh-554

Set the default sid from common properties.

Remove Servo from EurekaHealthIndicator.
Remove custom DataCenterInfo.
EurekaInstanceConfig.SID is now used as eureka id.
EurekaInstanceConfigBean.getSID falls back to metadataMap.instanceId for
backwards compatibility.

And also when using eureka-first for discovering config server.
The EurekaClient is very rigid and initializes itself, registering
with the remote service on instantiation. Hance it needs to be
in @RefreshScope for it to be properly refreshable. Doing that
leads to a sequence of other changes (e.g. to account for the
fact that there is no @RefreshScope in bootstrap context).

Fixes gh-551

fixes gh-534

When the parent (bootstrap) context registers the app as well as consuming
the registry it causes problems, e.g. when you refresh that context is
re-created and destroyed, which tends to unregister the app and it's hard
to get it back. It is simpler if the parent context use eureka read-only.
To ensure this we have to remove the @EnableDiscoveryClient from the
bootstrap context.

Tested with vanilla config server and eureka with the 'eureka-first'
sample and the 'zuul-proxy-eureka' sample.

Fixes gh-421

Reverts part of a change made for gh-349 and rationalizes a bit of the
Eureka configuration. The Eureka client cannot be shutdown without
attempting to restart it (but there isn't an obvious public API for
that), so it's better not to shut it down at all.

See gh-421

Move turbine/hystrix amqp specific implementations to spring-cloud-stream based implementations and let the user decide which broker to use.

fixes gh-545

1.4.15 isn't in maven central yet

fixes gh-534