* pr/3807:
  Polish
  Fix springloaded version

Closes gh-3800

Closes gh-3807

Conflicts: MessageSourceAutoConfiguration.java

Fixes gh-3803

Fixes gh-3782

Previously we had to create a fake Properties object as the factory did
not provide individual setters for the SSL configuration. This has been
added as part of Spring AMQP 1.5.0.RC1 so we're using those instead.

Closes gh-3754

Checking for a prefix "counter." is more correct than "counter" because
the readers (repositories) assume the former prefix is there.

Fixes gh-3801

Closes gh-2899

This commit enhances RelaxedDataBinder to include information about the
origin of a property (its original name before any prefix was removed
and its source) when it encounters an unwritable property. For example,
launching an application with a SERVER_HOME environment variable
configured will produce the following failure message:

Failed to bind 'SERVER_HOME' from 'systemEnvironment' to 'HOME' property
on 'org.springframework.boot.autoconfigure.web.ServerProperties'

Closes gh-3778

Closes gh-3781

Previously, manual meta-data were added to the existing set of entries
which could lead to duplicates if a manual entry is meant to complement
a property that is detected via the processor.

We now match the name and type of the item against the auto-detected
entries. If no match is found, we add the extra entry as we did before.
If a match is found we override the description, default value and
deprecation information.

Closes gh-3562

See gh-3792

Closes gh-3792

* pr/3793:
  Fix link to exec maven plugin

Closes gh-3793

Closes gh-3787

Previously, `ResourceUrlEncodingFilter` was registered even if the
resource chain handling was disabled (which is the default).

We now take care of registering it only if the resource chain handling is
enabled.

Closes gh-3353

Given that Spring Boot uses java config accross the board, a new `value`
attribute is now aliased to the existing `classes` attribute such that
one could write the following:

@SpringApplicationConfiguration(MyConfig.class)
public class MyTest {}

Closes gh-3635

Changing the velocity view resolver to a VelocityLayoutViewResolver seems
a common use case so it has now a dedicated section in the relevant how
to.

Closes gh-3732

The default value of `spring.devtools.restart.exclude` is quite long and
any override requires to copy/paste it to add additional exclusions. To
avoid that, a new `spring.devtools.restart.additional-exclude` property
has been added.

Both properties are now used to compute the full list of exclusions that
is used by PatternClassPathRestartStrategy.

Closes gh-3774

Closes gh-3773

Prior to this commit, the devtools used bean factory post processors to
configure the environment with custom, development-time properties. This
meant that the environment was configured as part of the application
context being refreshed. Crucially, this happened after any property
conditions were evaluated making it impossible for the devtools to
change the default auto-configuration behaviour for a bean or
configuration class that was conditional on a property.

This commit moves the configuration of the environment into an
ApplicationListener that listens for the
ApplicationEnvironmentPreparedEvent which is published as soon as the
Environment has been prepared and before the application context is
refreshed.

Closes gh-3726

The commit introduces a new extension point, EnvironmentPostProcessor,
that can be implemented by classes that want to modify the
environment. Implementations of EnvironmentPostProcessor are loaded
via spring.factories and called in response to the
ApplicationEnvironmentPreparedEvent. Application listeners that wish
to work with the post-processed environment can continue to listen
to ApplicationEnvironmentPreparedEvent and order themselves to
run after EnvironmentPostProcessingApplicationListener.

Existing ApplicationListeners that modify the environment have,
where possible, been updated to implement EnvironmentPostProcessor
instead.

Closes gh-3737

Conflicts:
	spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/HealthIndicatorAutoConfiguration.java

The DataSource health indicator uses `JdbcTemplate` behind the scenes
but nothing was checking that it is actually available.

`DataSourcesHealthIndicatorConfiguration` is now disabled if
`spring-jdbc` is not on the classpath.

Fixes gh-3765

* pr/3721:
  Fix typo

Closes gh-3721

* pr/3752:
  Fix table layout

Closes gh-3752