Spam prevention proposals

[Dave Johnson]

I added some specific proposals for spam prevention/management, some 
for Roller 2.1 and some for later releases:

   
<http://rollerweblogger.org/wiki/Wiki.jsp?page=Proposal_SpamPrevention>

Each of these could/should be written up into a more detailed 
proposal/design, but I'd like to get some feedback first, if possible.

- Dave