KRA install: show installation message only if install really started
Message that installation started/failed was shown even when
install_check fail (installation itself did not start).
This commit show messages only if installation started.
Enhacement for https://fedorahosted.org/freeipa/ticket/5455
Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>