Plugin ClamAV: Updated copyright and author informations. Changed the default configuration values ​​for the logging, so Mailgraph can display the found viruses.
Plugin OpenDKIM: Updated copyright and author informations.
Plugin Postscreen: Updated copyright and author informations.
Plugin RoundcubePlugins: Updated copyright and author informations.
Plugin SpamAssassin: Updated copyright and author informations.
Merge pull request #17 from reneschuster/master

Updated plugins copyright and author informations.