Adds a check for an empty URI in updateToHttpsIfNeeded

Add the ability to provide a default ZuulFallbackProvider

Fixes gh-1414

#1203 Improve filter performance by using only one instance of AllEncompassingFormHttpMessageConverter (#1681)

Currently all errors during writing to the outputStream are ignored. So the
response is read to the end. This is a problem when the response is
infite or very long running (`hystrix.stream` for example) and results in the
socket never being closed and eating up threads (on zuul and the proxied
backend). With this commit the errors during writing are not ignored resulting
in closing the response.

fix gh-1672, support @RequestParam without a value

Also adds minimal javadoc to classes.

See gh-1435

gh-1641: Fixed instructions for configuring EurekaIntanceConfig in AWS

Fixes gh-1663

* pull1656:
  Separate adding X-ForwardedProto header

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

This reverts commit 46ee0ce1.

maintain multipart content type for data parts

Fixes gh-1581

As discovered in #1643, using `@Configuration` on a custom configuration with `@FeignClient` is unnecessary and creates extra work for exclusion from a `@ComponentScan`. This updates the docs to make this explicit.

A new version of httpclient introduced by boot changed the behaviour that previously allowed the charset. It now has to be parsed out and passed to the apache `ContentType` object explicitly.

fixes gh-1649

ZuulProperties.ZuulRoute consturctor missing explicitly setting of customSensitiveHeaders boolean