Add the ability to automatically forward mail in whitelist

[kblief]

Question/Issue Overview

It would be advantageous to have a whitelist of email addresses that would automatically be forwarded to the whitelisted email address

Expected Behavior

Email received where the recipient is in the whitelist will have mail forwarded automatically

Current Behavior

All mail received is stored and can be manually forwarded.

[barryoneill]

Nice idea - Might want to consider supporting wildcard domains etc.

Would prefer to avoid an admin interface (at least, do we?), could achieve this for the interim through the configuration in /etc/holdmail.properties.

BTW - probably some overlap with #29