Allows feign/ribbon users to use standard config files rather than creating a bean of Request.Options.

fixes gh-696

When fallback beans are created, there was no longer a unique bean of the feign interface which caused autowire problems.

fixes gh-899

fixes gh-908

fixes gh-907

Typo in example code for `DiscoveryClient`

`DiscoveryClient` field declared with name `discoveryClient` but `serviceUrl()` method uses `client`.

* rxjava-stream:
  Spring Mvc RxJava integration.

Support for Single via a ReturnValueHandler.
Support for Observable via SseEmitter.

fixes gh-902

fixes gh-749

typo fixed

* feignExpanders:
  Where a given String conversion is supported, register Feign Param.Expanders backed by a Feign-specific FormattingConversionService.

backed by a Feign-specific FormattingConversionService.

fixes gh-881

See gh-896

fixes gh-897

Fixes gh-891

8.15 version of Feign breaks VND content types

fixes gh-886

fixes gh-882

fixes gh-880

I'm not sure that is a good thing though.

Fixes gh-873

For compatiblity with Angel streams we only need to set the content
type explicitly.

Fixes gh-873