Ability to configure client to send default headers #284 at 2.2.x (#420)

* Implemented ability to provide default query parameters and headers to feign clients.
Issue was mentioned in №284

* Removed wrong names of test data. Replaced with correct ones.

* Thread sleep was repalced with more verbose TimeUnit sleep

* Fixed more names of the clients.

docs/src/main/asciidoc/spring-cloud-openfeign.adoc

@@ -175,6 +175,10 @@ feign:
         loggerLevel: full
         errorDecoder: com.example.SimpleErrorDecoder
         retryer: com.example.SimpleRetryer
+       defaultQueryParameters:
+          query: queryValue
+        defaultRequestHeaders:
+          header: headerValue
         requestInterceptors:
           - com.example.FooRequestInterceptor
           - com.example.BarRequestInterceptor
@@ -188,6 +192,8 @@ Default configurations can be specified in the `@EnableFeignClients` attribute `
 
 If you prefer using configuration properties to configured all `@FeignClient`, you can create configuration properties with `default` feign name.
 
+You can use `feign.client.config.feignName.defaultQueryParameters` and `feign.client.config.feignName.defaultRequestHeaders` to specify query parameters and headers that will be sent with every request of the client named `feignName`.
+
 application.yml
 [source,yaml]
 ----