Uses configuration from IConfigClient reference to always use the most up to date configuration.  Fixes #1481.

Defaults were set too late and were overriding values set in the environment.

Specifically, spring.application.name took precedence over eureka.instance.appname.

 fixes gh-1516

Specifically, add `@ConditionalOnBean(EurekaClient.class)`.

Fixes an issue where eureka and ribbon are on the classpath, eureka.client.enabled=false which would cause a bean not found exception.

fixes gh-1511

This reverts commit cdaa97c0.

Make Netflix Servlet 3.0.1 compatible

This reverts commit be8eece9.

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