fixes gh-589

* metrics-test-fixes:
  Fix flaky Servo tests by avoiding DefaultMonitorRegistry

* metrics:
  Expanded metrics support to include Servo, Spectator, and Atlas

* For Java 8 users, Spectator is the recommended metrics library as Servo is now deprecated in favor of Spectator
* Servo support now needs to be specifically enabled via @EnableServo, even if servo-core is included on the classpath
* Added starter modules for both Spectator and Atlas support
* ServoMetricReader defines a convention for mapping tag-based metrics to hiearchical names for rendering by the Actuator /metrics endpoint

fixes gh-630

It still isn't actually used (and would only be used on a link to
a non-existent JSP page), but at least it can render now.

See gh-628

Fixes gh-628

fixes gh-525

get's eureka branding back.

fixes gh-627

Health check fails on commands without circuit breaker.

* feign-parameter-processors:
  Feign annotated parameter processors

For extensibility by connectors

We have to ensure that the ZuulController is not mapped on a
forward otherwise we just go back through the same code
path and render nothing.

Adds support for feign-hystrix

fixes gh-606

fixes gh-600

see https://github.com/Netflix/Hystrix/pull/927

User can provide a url in the route that starts with "forward:"
(instead of "http:" etc.) to handle the request locally.

Also properly ignores ignored routes, so they can be handled locally
(rather than giving up and sending 404).

Fixes gh-536

* pull588:
  Add isDebugEnabled() check

It is good thing to make this checks because of expensive concatenation of String objects (debug messages).

fixes gh-596

fixes gh-591

fixes gh-527

Helps when eureka is on the classpath, but is explicitly disabled.

fixes gh-521

Move it back to EurekaDiscoveryClientConfiguration.

fixes gh-578

Since all feign clients now have access to the type, logging can apply a type regardless.

Fixes gh-431