We need to be able to associate multiple social providers with an IDM user. At the moment
this is not based on the username of the account (for example google.23897892sdf). This
has to main drawbacks:
* Horrible username
* Can only associate a single social account with an IDM user
What is the best way to store this information? We mainly need to store what social
providers a user has linked and the social userid. In the future we may also want to
associate access tokens as well. We also need to lookup a user based on the social
provider + social userid.