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.

This reverts commit a628ba1b.