new_user.cgi is confusing to users who already have GENI-created gmoc-db contact entries

[chaos@bbn.com]

When a new user browses to ​http://gmoc-db.grnoc.iu.edu/protected/, they are invited to login, and eventually prompted to create a new account using OpenID credentials. (Text: "if you would like to create a new GMOC account click here")

If they try to create an account using the e-mail address which is associated with their slice authority account, then there is already an entry in the gmoc-db contact table with that e-mail address. So the UI will refuse to create a new account, and gives the error: "This email is already in use."

This is confusing to users who did not intentionally create the account, and have no reason to expect that gmoc-db created one for them due to their GENI identity. Add some explanatory text to that message, indicating that if the user already has an identity at a GENI slice authority or clearinghouse affiliated with that account, gmoc-db may have automatically created their account for them, and they can request a nonce to gain access to it.