Adds an `@ExportMetricReader` which was missing before and
led to people losing their metric exports when they had Servo
on the classpath.

Also allow servo metrics autoconfiguration to be disabled via
a flag netflix.metrics.servo.enabled=false (as an alternative to
excluding the class in `@EnableAutoConfiguration`).

The zone for a remote server comes from its
eureka.instance.metadataMap.zone, but we didn't (until this change)
apply the same logic to the client. If the client is registering
itslef with eureka then it will have a metadataMap itself and
we should be able to just reverse the logic.

Fixes gh-991

to ensure compatibility with legacy apps

Fixes gh-989

Makes use of StringUtils.commaDelimitedListToStringArray

Fixes gh-980

Users will have to switch from health.hystrix.enabled to
management.health.* for consistency with other health
indicators.

Fixes gh-985

so they don't appear on the dashboard

Fixes gh-974

fixes gh-987

Fixes proper RestTemplate behavior.

fixes gh-986

Fixes gh-894

Protects us against changes in Spring Boot 1.4 where the naming
convention changes.

Spring HttpMessageConverters can modify headers. This change passes the modified headersr back to the feign request, so the proper headers are sent on the request.

 fixes gh-977

The descriptions of name/serviceId/value and url were out of date
(name is mandatory now and can be mixed with url).

fixes gh-968

Route specific sensitiveHeaders override global.

fixes gh-944

* pull945:
  Ribbon retry works & fix Content-Length error.

This change requires setting `ribbon.http.client.enabled=true`.

This change addresses issue #648 Getting Retry Working In RestTemplate. There is also a fix in place that addresses the issue #357 RestTemplate Error.

fixes gh-648

fixes gh-961

* pull883:
  Send 404 in zuul servlet when no route is found.

Fixes false 200 in zuul when using zuul servlet rather than mvc servlet.

Fixes gh-865

fixes gh-957

fixes gh-956

fixes gh-955

fixes gh-954

Fixes gh-352

https://github.com/Netflix/eureka/releases/tag/v1.4.5

restores http basic auth.

Fixes gh-948

Fixes gh-642

* pull933:
  Adding the ability to specify a custom retry handler in the ribbon client configuration.

fixes gh-931

fixes gh-932