When a user enters a CLI with a StringFlags or StringSliceFlags and does not add
a value the CLI mistakently takes the next option and uses it as a value.
This usually ends up with an error like not enough options or others. Some times
it could also succeed, with weird results. This patch looks for any values that
begin with a "-" and return an error.
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
