fixes gh-2028

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

use only default https ports for https check

Deprecates RetryableStatusCodeException 

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

fixes gh-1795

The timeToLive and timeUnit parameters added to configure connection pool.

Fixes gh-1720

fixes gh-1956