TODO.txt

Username/Displayname
* display_name added to Auth_ID
* With multiple accounts referencing single ID, how do we know what 
  the display name should be?

Multiple Accounts
* Associate account mechanism
** Add another association
** Takeover/merge existing association (which auth_id wins?)
** allow duplicate login types? i.e. assign two twitter accounts, two 
   local login accounts?
** change password - we need to know whether we have any local auth 
   accounts. Which one gets changed? Selector box to choose?

Email Issues
* Activation Email
* Require email
* Email Verification
* Email Authentication
* FormEncode optional validation of email
* Unique Email address requirement

UX Issues
* add more detail to exceptions

SQL Issues
* unique index on auth_user_group on user_id,group_id