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 1.10+, once it was released.

  Requires fixing of https://issues.apache.org/jira/browse/CONFIGURATION-556
  and https://issues.apache.org/jira/browse/CONFIGURATION-557).

- some PMD fixes