Merge pull request #11 from hgschmie/config-fixes

Fixes for ness-config
Match commons-configuration interface declaration for ImmutableConfiguration.getList
Dependency bumps
[maven-release-plugin] prepare release ness-config-2.3.1
[maven-release-plugin] prepare for next development iteration
Fixes for ness-config

- Fix bug in ConfigProvider when setExporter is called before setConfig
  by guice (in which case the bean would not be exported). Add unit test.

- prepare code for commons-config 1.8+ (don't upgrade yet because of
  https://issues.apache.org/jira/browse/CONFIGURATION-556)

- some PMD fixes