Ribbon and simple host reverse proxy now share quite a lot of
code (everything to do with headers).

Fixes gh-103

Fixes gh-103

removed circular dependency between EurekaClientAutoConfiguration and EurekaDiscoveryClientConfiguration that caused DiscoveryClientConfigServiceBootstrapConfiguration to fail.

fixes gh-99

If user adds auth.route.<service>.scheme: passthru then instead
of adding the bearer token the filter will not do anything
(and the normal authorization header will be passed through
to the backend)

See gh-19

Without this change the health status is always UNKNOWN because it
never finds the servo metrics for the health indicator. It's also
a general spruce up of the servo and eureka metrics and health
infrastructure which was looking a little more complicated than
it needed to be (no need for a separate MetricReader).

Using Spring as an object factory to control the lifecycle of ribbon clients.
So far we have a single, parameterized configuration class for all clients, but
can be extended to allow user to supply additional configuration. The current
model for user extensions is

@EnableRibbonClient(@RibbonClient(name = "foo", configuration = FooConfiguration.class))
public class MainConfiguration {
    ...
}

So in this example, MainConfiguration is part of the "main" application context
and FooConfiguration is used to create the Ribbon client and load balancer for
the "foo" service.

Document FeignClient

fixes gh-91

fixes gh-85

fixes gh-87

Fixes gh-86

The default behaviour is now to strip the prefixes (global and
route-specific) by default. E.g.

zuul:
  prefix: /api
  routes:
    customers: /customers/**

Will forward /api/customers/101 to /101 on the customers service

See gh-43

Fixes gh-43

Handle InstanceRegisteredEvent and RefreshScopeRefreshedEvent in ZuulHandlerMapping rather than ProxyRouteLocator.
Move /routes endpoint out of ZuulHandlerMapping into RoutesEndpoint (because of a problem when I added @RefreshScope to ZuulHandlerMapping)

We now support prefix stripping per service, e.g.

zuul:
  routes:
    customers:
      path: /customers/**
      stripPrefix: true

Will route /customers/101 -> /101 (on the customers service)

See gh-77

User can now specify zuul.routes.*.{path,url,serviceId} (with
"url" and "serviceId" mutually exclusive (and "location" is a
synonym) separately, or can use a one-one short form, like the
old style.

See gh-77

zuul.route -> zuul.routes
zuul.mapping -> zuul.prefix

removed classes now in spring-cloud-commons

Bean instantiation ordering was causing external (user-supplied)
filter beans to replace the defaults, not append to them. Separating
out the autowired map of beans into a spearate class was enough to
fix it.

Fixes gh-78

fixes gh-73