Add feign-slf4j support.

fixes gh-178

The main problem here was the ZuulProperties being used everywhere. I also
took the opportunity to thin out the top level zuul package and keep the
web and route locator pieces in sub-packages for readability.

Fixes gh-172

A cleaner separation of ribbon and the eureka-dependent ribbon
configuration is achieved by adding a BeanPostProcessor to do the
ServerList wrapping, instead of doing it for every single ribbon
client.

See gh-172

proxy DiscoveryHeartbeatEvent's from parent to child be publishing a EurekaHeartbeatEvent and having zuul listen for EurekaHeartbeatEvent as well.

fixes gh-171

Fixes gh-153

fixes gh-153

Fixes gh-160

 fixes gh-147

fixes gh-149

Conflicts:
	spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClient.java
	spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientScan.java
	spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/RibbonRoutingFilter.java
	spring-cloud-netflix-turbine-amqp/src/test/java/org/springframework/cloud/netflix/turbine/amqp/AggregatorTest.java

This change adds an ApplicationListener that sets some high priority
properties in the Environment to allow server.port and management.port
to keep their usual meaning, but have server.port apply only to turbine.
Actuator endpoints can be enabled with management.port (different to
server.port otherwise there will be a conflict between Netty and Tomcat).

Fixes gh-143, fixes gh-140

Fixes gh-151

Fixes gh-156

fixes gh-129

fixes gh-135

created hystrix.stream.amqp.send-id to allow disabling of sending the context id as the metric id.  Turbine AMQP then defaults to serviceId:host:port

fixes gh-131

Now they match better what the vanilla /trace data does in terms of
object and field names.

Not used by the app itself, but will show up in metadata reports
and in tooling, so useful for documentation purposes.

See gh-125

Fixes gh-125

Fixes gh-126