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

Consistent with Spring MVC (and untested up to now apparently).

Fixes gh-874

Fixes gh-872

i.e. user sends multiple files with the same parameter name.

Fixes gh-870

fixes gh-731

fixes gh-695

fixes gh-542

fixes gh-857

Upgrade RxJava to 1.1.1

fixes gh-866

fixes gh-859

fixes gh-530

By default we now discard all Set-Cookie and Cookie headers. User
can manipulate it per route via zuul.routes.*.sensitiveHeaders, or
globally via zuul.ignoredHeaders.

fixes gh-854

fixes gh-847

Latest Eureka from Netflix uses a different HTTP client, and it
ignores the HTTP basic credentials in a service URL. This change
partially restores the old behaviour by providing an interceptor
(ClientFilter) that has a single, global username/password
taken from the first serviceUrl that contains credentials.

Fixes gh-849

Any client that wants to can include it back again, but generally
it only causes problems (XML returned from apps instead of
JSON by Spring MVC for instance). In general it only causes problems
for services whose clients use "Accept: application/xml,*/*", for
instance (like a browser).

See gh-306

Eureka now has the option (maybe always there) to not register
and that's a sensible default in the bootstrap phase (when we
might not know the port yet).

This reverts commit 3f34ccc8. We
need to discuss a bit more (that thread local is probably unavoidable
given the design of Feign, but I don't like it yet).

See gh-841

Some slightly tricky manipulation involved here, but hopefully
UriTemplate to the rescue.

Fixes gh-682

Automatically registers Spring conversion-based Feign Expanders
when available

Fixes gh-841

Spring MVC Feign Contract did not support parameter name fallback
for the #value() attributes of known parameter annotations. Makes
this feature available when the interface has been compiled with
the Java 8 -parameters compiler arg

Fixes gh-835