- ad.module

    o make hostid accessible
    o set absolute path in the redirect url
 - ad.install
    o convert redirect urls to absolute paths
 - ad_remote.module
    o simple proof-of-concept for hosting ads on remote websites
 - adserve.php
    o add hostid to redirect URL
 - ad_image.module
    o use @HOSTID___ token so hostid can be set in cached content
 - ad_text.module
    o use @HOSTID___ token so hostid can be set in cached content