Bug introduced with Improvement #12891

[pkolmann]

Description:

When I added the patch to support the DisplayName as FullName field (see #12347) I used displayName as primary possibility, then CN and last userName.

@kukkjanos with your new patch in #12891 you changed that to CN, userName, displayname.

I have now the issue with our setup, that we don't get a CN from our SAML IdP, but we get username and displayName. Everyone gets now the username set as displayName.

@kukkjanos would it be ok for you to change it to CN, displayName, username or ok if I send a pull request for that?

Thanks
Philipp

Steps to reproduce:

1.) have SAML Login
2.) only have username, displayname, email attributes in the saml reply
3.) login as a new user
4.) See username as Full Name set

Expected behavior:

Use DisplayName as Full Name of new account

Actual behavior:

username is used as Full Name of user

Server Setup Information:

• Version of Rocket.Chat Server: 1.1.1
• Operating System: Debian 9
• Deployment Method: tar
• Number of Running Instances: 8
• DB Replicaset Oplog: Enabled
• NodeJS Version: v8.16.0
• MongoDB Version: 3.2.11