Use 60-dkim for the key-definitions on systems with seperated amavisd-configs like debian and ubuntu

Use preg_match/preg_replace when adding/removing keys to amavis to avoid duplicate keys with different selectors. Prevent restarting amavis more then one time.

the path for the dkim-keys is automaticly creaed by the server-plugin, the path could be empty in the interface, and the amavis-template for gentoo was updated

add amavis-configfile-location for centos 6.4; add amavis-initscrip-name for centos 6.4; fixed missing private_key in mail/mail_domain_dkim_create.php

display dns-record for dkim in the mail-domain
rewrite function domain_dkim_update in server/plugins-available/mail_plugin_dkim.inc.php
change dns*.php according to commit 604c0c24

skip writing dkim-values for inactive domains
removed the public-dkim-key from the interface
added german language-file

- Added dkim installation to installer.
- Added backup filesize in backup cronjob.

Reverted SVN trunk back to revision 3938 to remove changes in default theme an a replacement of the ispconfig logo.