Updated the copyright notice according to these two articles:
* http://www.plagiarismtoday.com/2011/11/08/how-to-write-a-copyright-notice/
* http://www.arcticllama.com/blog/beingafreelancer/proper-copyright-notice-on-websites/
Added missing translator credits for Dutch.
These names were restored from old PO files.
Credit TuxFamily for hosting getgnulinux.org