Adding default provider url to authmap table for new users

I believe users shouldn't be expected to add the site's openid to their providers list in their profile. The openid_sso_provider module hides this tab for regular users making it impossible to add this field.

For reference, I am using openid_provider, xrds_simple, openid_sso_provider and openid_sso_relying for in a simple signon set up in drupal 7. I'm hoping to help make these modules more stable. I've added the openid to the authmap table in hook_user_insert() so new users won't have to worry about openids when signing in. It will just work. Going to roll a patch now.