reduced log level for some messages
limited Extra Columns Plugin support
Update docs to reflect working monkey-patch method

Monkey-patching changed post https://github.com/jenkinsci/job-dsl-plugin/commit/3bf55f83e1087f2f2ca945d353e869884178cf66
and you need to `use(common) { job { ... } }` now.
fixed problem with buildDescription
added an entry to the release notes
[JENKINS-22862] DSL for Maven Deployment linker plugin
- Added unit tests
- Updated documentation