Include documentation that covers caveats and use cases

Use cases:
- Security on high-access accounts
- Intranet security (matching to specific machines)
- Prevent multiple-registrations

Caveats:
- Proxies
- Shared machines / public machines
- Mobile IPs very dynamic
- DHCP in general
- Proxies

Full discussion:
http://compo.sr/forum/topicview/misc/deploying/points-awarded-before.htm?post_id=108423&keep_refreshed_once=1#post_108423

This should just be done using a firewall or .htaccess rules.

Building it into Composr is too problem-filled. If someone would understand the complexities, they'd be most comfortable doing it at the web server level anyway.