Use python2 for ipa cli
    
    Switch 'ipa' command to py3 has been done prematurely, this commit sets python2 as interpreter for ipa cli.
    
    https://fedorahosted.org/freeipa/ticket/5638
    
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>