Fixed package tangle between w.r.f.RequestPredicates and w.r.f.support.RequestWrapper.

Issue: SPR-14538

Issue: SPR-14682

Issue: SPR-14726

Issue: SPR-14645

(cherry picked from commit ace25d49)

Move the AbstractServletHttpHandlerAdapterInitializer together with
the other two base classes in spring-web-reactive. Since the
interface is in the web package, this avoids a package cycle.
Also add a mention in the reference.

Issue: SPR-14713

This commit introduces three new WebApplicationInitializers for use with
Spring Web Reactive:

 - The AbstractServletHttpHandlerAdapterInitializer registers a
 ServletHttpHandlerAdapter that wraps a user-provided HttpHandler.

 - The AbstractDispatcherHandlerInitializer registers a
 ServletHttpHandlerAdapter that wraps a DispatcherHandler (or any
 WebHandler). The handler is provided with an application context.

 - The AbstractAnnotationConfigDispatcherHandlerInitializer is a
 subclass of the above, creating an
 AnnotationConfigApplicationContext based no provided @Configuration
 classes.

Issue: SPR-14713

This commit refactors the response body extraction logic into a separate
function: BodyExtractor. Standard populators can be found in
BodyExtractors.

This commit extracts the response body insertion logic into a separate
strategy interface: BodyPopulator. Standard populators can be found in
BodyPopulators.

This commit refactors the Router into a RoutingFunctions class, by:

  - Renaming the class :)
  - Moving all Configuration logic into a separate, top-level
  Configuration class with mutable builder.

Issue: SPR-14693

Issue: SPR-14693

Since appcache manifests can have various file extensions, developers
should register the (file extension, media type) mapping in their Spring
MVC / Reactive Web configuration.

This commit adds javadoc on both `AppCacheManifestTransformer` variants
to explain how to do that.

Issue: SPR-14510

Latest dependency updates (Undertow 1.4.3, EhCache 3.1.2, Caffeine 2.3.3, Rome 1.7, Woodstox 5.0.3, Jettison 1.3.8, JRuby 9.1.5.0, RxJava 2.0 RC2, RxNetty 0.5.2 RC4)

Issue: SPR-14725

Improve RootBeanDefinition to specify an AnnotatedElement that holds
qualifier information. When such element is present, any qualifier that
it defines will be used to find a matching candidate.

Issue: SPR-14725

Issue: SPR-14718

Issue: SPR-14669

Rather than setting the status to 503 directly from the timeout
interceptor which no longer seems to work reliably with Servlet
containers like Jetty even performing an additional ERROR dispatch back
to the original URL, we know rather set the DeferredResult to an
AsyncTimeoutException, which results in a dispatch and standard
handling within Spring MVC. This should be a more reliable way of
dealing with timeouts.

Issue: SPR-14669

Issue: SPR-14643

Issue: SPR-14703

Added readableChannel() to Resource, which returns a
java.nio.ReadableByteChannel. The default implementation uses
Channels.newChannel() to create a channel based on what is returned from
getInputStream(). Subclasses have more effecient, file-based
implementations.

Issue: SPR-14698

* pr/1172:
  Fix doc style

Closes gh-1172

This commit updates the two transformers to make them more
consistent with updates of their spring-web-reactive equivalents.

Issue: SPR-14521

Issue: SPR-14521

(cherry picked from commit 54db4968)

Issue: SPR-14709
(cherry picked from commit fbe7ddb6)