The CI build is failing, but, for some reason, the same tests are
working fine on developer machines. This commit increases the level
at which the logging calls are being made to severe in the hope that
some CI-specific configuration is filtering out the calls when
they're at info level.

Fixes gh-1753

Fixes gh-1612, Fixes gh-1770

1 disable the file output unless LOG_FILE is set
2 make the console optional

fixes: gh-1612

Fixes gh-1773

Then we can optionally find a non-anonymous principal if there
is one. If the user is anonymous then the health result is cached
up to endpoints.health.ttl (default 1000ms) to prevent a DOS attack.

Fixes gh-1353

Closes gh-1765

See gh-1762

This reverts commit d6621e62. I think
the test failure might be a bug in Liquibase:
https://liquibase.jira.com/browse/CORE-2094

Fixes gh-1382

Fixes gh-1752

Fixes gh-1762, gh-1731

Closes gh-1748
Closes gh-1703

Closes gh-1708

Closes gh-1742

Rework @TestPropertySource changes introduced in commit d251b513
to restore compatibility with Spring Boot 1.1

- Only add the `server.port` property when no @IntegrationTest
  annotation is found.
- Always add a default `spring.jmx.enabled=false` property.
- Restore the SpringApplicationContextLoader.getEnvironmentProperties
  protected method.
- Remove the @IntegrationTest.properties attribute.

See gh-1697

Previously, the regular jms connection factory was always overriding
the xaConnectionFactory when using ActiveMQ. While
ActiveMQAutoConfiguration is namely shielded with a condition on a
missing ConnectionFactory bean, said configuration class also imports the
XA and regular configuration classes that both can create the connection
factory.

This commit adds a ConditionalOnMissingBean in the second class that is
imported in case the XA configuration has already defined what it needs.

Fixes gh-1727

Closes gh-1740

Previously, Log4J2LoggingSystem did not install SLF4JBridgeHandler.
SLF4JBridgeHandler is used to route logging calls made using
java.util.logging into SLF4J. This resulted in entries being written
to System.err instead.

This commit updates Log4J2LoggingSystem to register the bridge handler
thereby ensuring the logging that originates into java.util.logging is
routed into SLF4J. This change has been made by extracting a new
abstract superclass that performs the registration. This super class is
extended by all SLF4J-based LoggingSystem implementations.

Fixes gh-1737

Previously, there was a timing window where the output file had been
created but it was empty. This would cause the test to fail as the
output was read from the empty file and didn’t match the expected “Hello
World”.

This commit updates the test to only process the resources in the output
directory when all the resolved resources have a non-zero content
length. An @Before method has also been added to delete the output
produced by the test so that the outcome of the test isn’t affected by
files generated by previous runs.

Fixes gh-1735

This is a follow-on from the changes made in 2b7bf3e7. In addition to the
problematic use of @ConditionalOnClass that was addressed in 2b7bf3e7,
JerseyAutoConfiguration also used @ConditionalOnBean referencing a 
Jersey class. This has the same problem when used on a class that
implements WebApplicationInitializer. Implementing
WebApplicationInitializer causes the class’s annotations to be
introspected during servlet container initialiser processing. If a
@ConditionalOnBean annotation references a Class that cannot be
loaded an ArrayStoreException occurs.

This commit updates JerseyAutoConfiguration to reference ResourceConfig
as a String. This allows it annotations to be introspected without
attempting to load a Jersey class that may not be on the classpath.

Fixes gh-1733
Fixes gh-1719

For those running applications on Java 8, dependency management for the
Java 8-compatible artifact is also provided.

Closes gh-1721

Previously, Bitronix's server ID was hard-coded to be
spring-boot-jta-bitronix. This created the possibility of multiple
transaction managers performing recovery on each other's behalf as
they would be unable to identify their own XIDs due to the common
server ID.

This commit reinstates the default (which is the IP address of the
machine on which Bitronix is running), and introduces a new
property, spring.jta.transaction-manager-id, that can be used to
configure the id for both Atomikos and Bitronix. A cautionary note
has also been added to the documentation for Atomikos and Bitronix
explaining the need to configure this property.

Closes gh-1548