bad argument parsing not throwing an error with SDK v0.16

[jspaleta]

This appears to be a regression in v0.16 from previous releases, not sure how far back this goes.

When passing a bad argument for example "--gross icky" the output reads "Error executing blah-blah-plugin: unknown flag: --gross" but the return status is 0.

The return status should definitely be non-zero to help plugin users diagnose the problem.

This isn't solvable inside the plugins using the sdk. The sdk actually forces exits prior to any plugin specific business logic runs such as a checkArgs function