Make ipa-client-install error messages more understandable and relevant.
* Check remote LDAP server to see if it is a V2 server
* Replace numeric return values with alphanumeric constants
* Display the error message from the ipa-enrollment extended op
* Remove generic join failed error message when XML-RPC fails
* Don't display Certificate subject base when enrollment fails
* Return proper error message when LDAP bind fails
https://fedorahosted.org/freeipa/ticket/1417