We allow users to configure LDAP attribute preferences. For example,
email can be configured to use `mail`, `email` and `userPrincipalName`,
falling through to the next until a value is found. Prior to this
change, Gitlab::LDAP::Person did not honor this configuration. Now,
the class will honor `name` and `mail` configuration. It does not
handle `username`, or fallback to `first_name` + `last_name` in the
absence of `name`.
The Net::LDAP::Filter.escape function can not be used to escape the DN name because the backslash is required to escape special chars in the DN name. This leads to the error message "Access denied for your LDAP account." and prevents the user from logging in to gitlab.
Example DN:
CN=Test\, User,OU=Organization,DC=Company
CN=Test User,OU=Organization,DC=Company
http://www.ietf.org/rfc/rfc4514.txt
