* pr/8215:
  Allow property expansion for *.yaml

Closes gh-8215

This commit improves `SimpleRabbitListenerContainerFactoryConfigurer` to
use a custom `MessageConverter`. If such a bean is present, it is used
for the default factory that is auto-configured.

Closes gh-8194

In Gradle 3.3, when an API that will be removed in 4.0 is called, a
deprecation warning is output as part of the build. Users have noticed
his warning and, quite reasonably, complained about it. Unfortunately,
avoiding the warning requires the use of an API that was introduced in
Gradle 3.x which we can't use directly as we want to remain compatible
with Gradle 2.x.

This commit introduces the use of reflection to call
ProjectDependency.getTargetConfiguration() via reflection when it's
available (Gradle 3) and ProjectDependency.getProjectConfiguration()
when it's not (Gradle 2).

Closes gh-8154

Closes gh-8146

Closes gh-8197

The changes made in 919d0c61 meant that the value of
spring.profiles.active or spring.profiles.include was only processed
when a single property source, the property source for the config file
being read, was available. This meant that any placeholders in those
values would only be resolved against properties in the configuration
file rather than against the entire environment.

This commit updates the binding process so that placeholder resolution
is not performed during binding against a single configuration file.
Once binding has completed, the bounds values are post-processed to
resolve and placeholders that they may contain.

The two-step process described above is used in preference to binding
against the whole environment. This avoids a problem with profiles
that are active or included by property sources in the environment
being processed repeatedly.

Closes gh-8234

* pr/8153:
  Fix an assertion in SkipPatternJarScanner

Closes gh-8153

The `spring-boot-test-support` module is internal and is not deployed so
we should not offer public dependency management for it.

Closes gh-8165

* pr/8226:
  Fix link in doc to Spring Test

Closes gh-8226

This commit qualifies the `CustomConversions` bean name that the Mongo
auto-configuration might create. `CustomConversions` is a common pattern
in Spring Data and other stores are using the same name.

See https://jira.spring.io/browse/DATASOLR-362

Closes gh-8225

Closes gh-8222

Previously, if the configured error controller responded with a
redirect to an error caused by an exception, standalone Tomcat would
render its default error page for the original exception. This
occurred because ErrorPageFilter sets the
javax.servlet.error.exception request attribute prior to dispatching
to the error controller and then does not clear it. As the request
unwinds, Tomcat's ErrorReportValve notices that the attribute is set
and renders an error page for the exception that is the attribute's
value.

This commit updates ErrorPageFilter to remove the
javax.servlet.error.exception and javax.servlet.error.exception_type
attributes upon successful completion of a forward to the error
controller. This prevents Tomcat from rendering an error page for
an exception that has already been handled by the error controller.

Closes gh-7920

Closes gh-5133
Closes gh-7886

This commit creates a separate
`ServerPropertiesServletContainerCustomizer` that holds the servlet
container customization code, separating that concern from the server
configuration keys.

See gh-8066