Ignore DataSourceAutoConfigurationTests.testExplicitDriverClassClearsUserName() as it fails without running mysql instance

To use a DataSource pool (Tomcat or DBCP) the user must supply a valid
driver class name *and* database URL. If both are supplied and the
driver class is not one of the embedded ones, then no default username
or password is provided.

Fixes gh-94

When running an application, --local can be used to collect the
application's dependencies in a local directory. Prior to
AetherGrapeEngine being introduced, using --local would result in the
dependencies being written to ./grapes. When AetherGrapeEngine was
introduced --local no longer had any effect.

This commit updates AetherGrapeEngine so that it honours --local,
writing its dependencies to ./repository. When --local is not specified
dependencies are written to ~/.m2/repository (the standard location
for the local Maven cache). As part of this change TestCommand has
been refactored so that it lazily initialises its GroovyCompiler. This
ensures that RunCommand has a chance to set the system property that
backs --local before AetherGrapeEngine is initialised and accesses the
property.

Fixes #99

Generate springcli.properties in generate-resources so that it can
be copied by the resources plugin in the process-resources phase.

Failing test cases weren't not properly handled and instead caused
test to break. Added a test case and verified it works for both JUnit
and Spock.

Previously: properties(Map) behaved differently to
properties(String...).

Fixed by merging the implementations.

Also added properties(Properties).

Previously the management endpoint filter was applied to all requests
if the user had disabled security.management.enabled, but since it
had no security applied it was letting all requests through.

The fix was to explicitly exclude the whole enclosing configuration
and carefully ignore the management endpoints in the normal security
chain.

Fixes gh-100.

3d714d30 allowed all integration tests to download snapshots and
milestones. The test for the integration sample, which depends upon a
milestone, no longer needs to be a special case.

Extract and refactor inner-classes from the GroovyCompiler to improve
code readability.

RelaxedDataBinder now supports "env var" style variables that include the
path prefix, e.g. FOO_BAR_BAZ=boom will bind to a bean with property "baz"
and a binder with prefix "foo.bar".

Fixes gh-98

Extract logic from SampleIntegrationTests into a reusable JUnit @Rule.

Aplly consistent formatting, drop JDK 8 support and cleanup repo
locations to use spring.io.

Update CLI SampleIntegrationTests to no longer disable snapshot repos.

- Found typo while reading.

Previously, Repackage would attempt to repackage every jar in the
project. This would cause it to incorrectly attempt to repackage source
and javadoc jars.

This commit updates Repackage so that it ignores any jar with a
classifier. Hopefully this is a reasonable approximation for ignoring
'special' jars that should not be repackaged such as sources and
javadoc.