Handling multiple authentication types

Updates to close out #44. 

* Moving authenticators into CDI providers
* Updating login form tags to handle LDAP login better
* Adding moderator group function to LDAP auth
I think I'll leave it for now. It's making two separate LDAP connections out of necessity; one to connect with the user's credentials, and one to grab user details (which usually requires an admin connection). The class does a fairly good job of making that management work well.