Document how to use thread isolation with hystrix and feign.  Fixes #1191.

Fixes gh-1462

fixes gh-1345

Use the new ServiceRegistry interface

Creates a new EurekaRegistration object that aggregates classes needed
for a single registration.

RxJavaReturnValueHandlerConfig can only be loaded when both spring-web
and spring-webmvc are on the classpath, because it contains a reference
to the WebMvcConfigurerAdapter class.

But the ConditionalOnClass annotation only included the class from
spring-web. In our situation, only spring-web was on the classpath,
resulting in a NoClassDefFoundError for WebMvcConfigurerAdapter. Fix it
by adding that class to the condition as well.

Emphasises that it's a black list, and clarifies that you need to
set it to empty to get authorization and cookie headers.

Document Hystrix Fallback For Zuul

Provide A Retry Policy For Ribbon Clients

-additional refactoring from changes in s-c-commons

Fixes gh-1363

Resolve spring.application.name via property resolver

Breaks Spring Boot 1.3 compatibility, enables 1.5

Instead of blocking them (which is the default behaviour of a
Spring MVC controller) Cors requests will flow through the Zuul
filters by default. Users can control it by grabbing the
ZuulHandlerMapping in a @PostConstruct and injecting some
CorsConfiguration via its setCorsConfigurations() method.

This fixes most of the issues people encounter when there are
multiple proxies in the request. The tricky thing is that there
is another header "Forwarded" that we don't recognize, but which
backends probably do, at least some of the time (since it is
from an actual RFC). The problem is that "Forwarded" does not
contain the ports, so Spring UriComponentsBuilder cannot use it
to rewrite links to a specific port. Since we do not support it
already, this change doesn't make things any worse, but the
corner case is there still.

Hystrix fallback support for Zuul routes.

Fixes gh-250.

Document Manual Feign Client Creation

Breaks Spring Boot 1.3 compatibility, enables 1.5

Moving eureka.server.{expectedNumberOfRenewsPerMin,defaultOpenForTrafficCount} to eureka.instance.registry so relaxed binding can be used. Default to old values for backwards compatibility.