ipa-client-install: create a temporary directory for ccache files
    
    gssapi.Credentials instantiation in ipautil.kinit_keytab() raises 'Bad format
    in credential cache' error when a name of an existing zero-length file is
    passed as a ccache parameter. Use temporary directory instead and let GSSAPI
    to create file-based ccache on demand.
    
    https://fedorahosted.org/freeipa/ticket/5528
    
    Reviewed-By: Tomas Babej <tbabej@redhat.com>