Previously, these were managed directly via archaius, but due to
some combination of changes in boot 1.5.x (likely a tomcat change as
zuul filters were initialzed in a servlet context listener) and Dalston,
The filter was created before archaius could be initialized.

The properties are backwards compatible and are in the
`ZuulProperties.Host` object.

fixes gh-1950

spring boot uses all high ports and there are some trouble if ports end with 443 (e.g. 24443, ...)

see gh-1950

Let SecurityContextConcurrencyStrategy be installed as the hystrix
concurrency strategy regardless of if feign's hystrix support is installed.

fixes gh-1969

The timeToLive and timeUnit parameters added to configure connection pool.

Fixes gh-1720

Fixes gh-1598

CounterFactory is used by ZuulException and was previously initialzed
with a dummy impl.

This adds a Spring Boot CounterService based implementation.

Also adds the ability to implement a zuul TracerFactory.

Add the ability for ribbon clients to specify response status codes they would like to retry.  Fixes #1540.

fixes gh-1824

Change /routes endpoint to use EndpointMvcAdapter and AbstractEndpoint.  

Fixes #1797

Added more unit tests

Add X-Forwarded-Port header in Zuul PreDecorationFilter
even with X-Forwarded-Host header being absent.