[det]openid_associate(+URL, 
-Handle, -Assoc, +Options)
[semidet]openid_associate(?URL, 
+Handle, -Assoc, +Options)Associate with an open-id server. We first check for a still valid old 
association. If there is none or it is expired, we establish one and 
remember it. Options:
- ns(URL)
 - One of 
http://specs.openid.net/auth/2.0 (default) or
http://openid.net/signon/1.1. 
- To be done
 - Should we store known associations permanently? Where?