Tomcat provide built-it support for gzip compression of HTTP responses.
This commit adds support for enabling and configuring this compression
via the environment using server.tomcat.compression and
server.tomcat.compressableMimeTypes.

See gh-2031

The ErrorPageFilter exposes a wrapped response to the downstream
chain and unless more care is taken the chain will be able to
set the response status, but not inspect it.

Fixes gh-2367

A dependency on org.glassfish.jersey.ext:jersey-bean-validation has
been added to spring-boot-starter-jersey. jersey-bean-validation’s EL
dependencies have been excluded in favour of those provided by
spring-boot-starter-tomcat (or starter-jetty or starter-undertow should
the user choose to use a different embedded container).

Closes gh-2315

Previously, JarCommand removed all @GrabResolver annotations in an
AST transformation. This was being performed as custom resolver
configuration is not necessary in a jar as all of the dependencies are
available from the jar. Furthermore, leaving the annotations in place
caused a failure when the jar was run due to a missing Ivy dependency
that's required by Groovy's default GrapeEngine, GrapeIvy.

The removal of @GrabResolver annotations was being done before they
could be used by Groovy's GrabAnnotationTransformation to configure
the GrapeEngine's resolvers. This resulted in the annotations having
no effect such that a dependency that was only available from a
repository made available by @GrabResolver would fail to resolve if
it was not cached locally.

This commit updates the AST transformation to leave the @GrabResolver
annotations in place but to set their initClass attribute to false.
This allows the annotation to be used while the jar's being compiled,
but supresses the generation of the static initializer that adds the
custom resolver to the GrapeEngine when the compiled code's run via
java -jar.

Fixes gh-2330

Previously, when LogbackLoggingSystem or Log4JLoggingSystem were
initialized during application start up, they would install SLF4J’s Java
logging bridge handler, however no corresponding uninstall was performed
during application shutdown. When deployed to a servlet container, where
the application’s lifecycle doesn’t match the JVM’s lifecycle, this lead
to a memory leak.

This commit updates LoggingSystem to introduce a new cleanUp method. An
empty implementation is provided to preserve backwards compatibility
with existing LoggingSystem subclasses. Both LogbackLoggingSystem and
Log4JLoggingSystem have been updated to implement cleanUp and uninstall
the SLF4J bridge handler. LoggingApplicationListener has been updated
to call LoggingSystem.cleanUp in response to a ContextClosedEvent.

Closes gh-2324

Closes gh-2352

Closes gh-2337

Closes gh-2334

Closes gh-2333

Closes gh-2358

Closes gh-2357

Closes gh-2336

Closes gh-2335

Add Atmosphere example application based on
http://github.com/Atmosphere/atmosphere-samples/tree/master/samples/chat

Closes gh-2341

Update WebSocketAutoConfiguration so that spring-websocket is no longer
required for WebSocket support.

See gh-2341

Previously, some classes that were annotatated with
@ConditionalOnWebApplication assumed that, if the application was a
web application, Spring MVC (spring-webmvc) would be on the classpath.
If it was not, the application would fail to start, typically with an
error relating to WebMvcConfigurerAdapter being unavailable.

This commit updates the affected configuration classes and annotates
them with @ConditionalOnClass(WebMvcConfigurerAdapter.class) to
ensure that their auto-configuration only takes effect if its a web
application and Spring MVC is on the classpath.

Fixes gh-2345

* pull2323:
  Fix copy/paste errors

Closes gh-2323

The package names changed a bit from the prototype project, but wuth vanilla
autconfiguration usage that shouldn't matter. Follows closely the Groovy
templates support. Templates live in classpath:/templates/*.html by default.

Fixes gh-2242

Update the "Relaxed binding" with a small table of common relaxed
property names and when they might be used.

Fixes gh-2234

See gh-2304

Extended RelaxedDataBinder to include a case insensitive version of
SEPARATED_TO_CAMELCASE. This allow properties of the form TEST_THE_VALUE
to to bound to a @ConfigurationProperties class with a prefix of "test"
and a field of `theValue`.

Fixes gh-2304

Use SourceVersion.latestSupported() rather than @SupportedSourceVersion
since we might build with an earlier JDK.

Fixes gh-2302

The last trailing `\n` is not required as the logging system will add
it.

See gh-2146

Fixes gh-2146

See gh-2288

See gh-2299

Make IntegrationTestPropertiesListener public so that it can be used
when @TestExecutionListeners are declared on a parent class.

See gh-2135