This commit updates Spring Boot to Liquibase 3.3.0 and makes the
necessary changes to Boot's PackageScanClassResolver.

Previously, when a class found by the scan could not be loaded a
warning message was logged. This commit lowers these to debug level,
bringing them into line with logging that the standard Liquibase
implementation does. It also avoids a warning always being logged at
startup due to Liquibase's WatchCommand$DynamicContentHandler which
depends on Jetty (an optional dependency of Liquibase).

Closes gh-1382

Fixes gh-1837

This reverts commit 6e041464.

Fixes gh-1830

Update ConfigurationMetadataAnnotationProcessor to ensure that only
local `additional-spring-configuration-metadata.json` files are merged
with the final output.

See gh-1830

Update ConfigurationMetadataAnnotationProcessor so that it gets called
even if the source code doesn't include any @ConfigurationProperties
items.

See gh-1830

Rename AbstractTemplateViewResolverProperties.setCharSet/getCharSet to
setCharset/getCharset, deprecating the old method.

Fixes gh-1835

Additional items added since 1.1.x

Fixes gh-1834

Conflicts:
	spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

Fixes gh-1834

Switch the Tomcat 8 and Jetty 9 samples to Tomcat 7 and Jetty 8. Since
Tomcat 8 and Jetty 9 are now the default versions the previous samples
are no longer relevant, however, we do need integration tests to check
that we remain compatible with Tomcat 7 and Jetty 8.

See gh-1832

Upgrade to latest versions of Tomcat and Jetty and to the latest Servlet
API whilst will remaining compatible with Tomcat 7 and Jetty 8.

Fixes gh-1832, gh-369

See gh-369

Change the pidfile property from `spring.application.pidfile` to
`spring.pidfile` (to save confusion with SpringApplication properties).

Also added documentation and meta-data information.

See gh-1579

Fix an issue where debug logging never occurred because it was guarded
incorrectly using isWarnEnabled().

Fixes gh-1780

Some were missing, some were named incorrectly.

See gh-1827

Rename 'additional-spring-configuration-metadata.json' to
'spring-configuration-metadata.json' and drop the annotation processor.

The project has no @ConfigurationProperties defined so the annotation
processor didn't kick in.

Fixes gh-1830

See gh-1831

* spring-boot-1412:
  Add fork option for mvn spring-boot:run

Closes gh-1483

Update RunMojo to include a `fork` option and change the default
to only fork if agent or jvmArguments are specified.

Fixes gh-1412

Update ApplicationPidFileWriter to support the Spring Environment,
picking up the `spring.application.pidfile` property if specified.

Fixes gh-1579

* gh-1777:
  Add PropertiesPropertySourceLoader test
  Add XML support to PropertiesPropertySourceLoader

Fixes gh-1777
Closes 1783

Create a PropertyNamePatternsMatcher strategy interface that
PropertySourcesPropertyValues can use to determine when a property
can be used.

PropertiesConfigurationFactory uses DefaultPropertyNamePatternsMatcher
which is heavily optimized for frequent calls.

Fixes gh-1823

Update ConfigurationPropertiesBindingPostProcessor to ensure that
the defaultConversionService is only created once.

Fixes gh-1822

Disable JTA auto-configuration altogether with a simple property. This
can be useful if the environment is JTA capable but the application does
not require it.

Fixes gh-1457

Enable ConditionalOnJndi evaluation and add tests that validate it works
as expected

Fixes gh-1820

Override the default StringHttpMessageConverter provided by the standard
Spring MVC configuration so that is uses UTF-8 instead of the aging
default of the servlet spec (that is ISO-8859-1)

Fixes gh-1800

Fixes gh-1816

See gh-1590

Fixes gh-1104