Don't show empty versions if binaries aren't installed
see also https://open.greenhost.net/openappstack/openappstack/merge_requests/114#note_5798
TASK [configure : Show current helm version] *********************************************************************************************************************************************
Monday 28 October 2019 13:49:40 +0100 (0:00:02.294) 0:00:34.612 ********
ok: [varac-test] =>
msg: 'Current helm version is: '
…
TASK [rke_configuration : Show current rke version] *****************************************************************************************************************************************************************************************************************************
Friday 25 October 2019 16:29:25 +0200 (0:00:00.148) 0:06:42.042 ********
ok: [oas.alumnicloud.net] =>
msg: 'Current rke version is: '
…
TASK [setup : Show current krew version] ****************************************************************************************************************************************************************************************************************************************
Friday 25 October 2019 16:34:18 +0200 (0:00:00.280) 0:11:35.249 ********
ok: [oas.alumnicloud.net] =>
msg: 'Show current krew version is: '