ncm-download: Fixed false failure bug, added noaction support

Fixed the problem where occasionally curl reported a failure (inspite of
using the option to prevent this) which caused ncm-download to
incorrectly report an error.

Modernised to include --noaction support. Component already had unit
tests in spite of using LC::Check::status. It turns out that
LC::Check::status *does* support noaction so is test safe.
@NZJourneyMan this looks good to me as long as https://github.com/quattor/CAF/pull/31 is merged in. 
if that PR is merged in, are you able to use it (and change back the code) or do you need these fixes with an old CAF version?