openid id field doesn't seem to be consistent for the same openid login about marmoset HOT 3 CLOSED

They're computed by Google, and then we hash them. The identifier from google 
is computed partially based on the openid.realm param or the openid.return_to 
param if realm isn't found. So I think what we need to do is call setRealm() on 
the AuthRequest before sending it. It's possible that different return_to urls 
are causing the problem. Will look into this.

This should be fixed, see [1]. Addressed this in 2 ways:
1. More consistent realm, set per-request. Note that using different urls to 
access same submit server can still result in different IDs from google, which 
is addressed by
2. If the returned ID is from google, we use the email address instead of the 
OpenID as the user's id.

[1] 
http://code.google.com/p/marmoset/source/detail?r=c5ba1d43030fb0344e5723886de8e5
84e1389551