Exit with non-zero RC on failure #778

Is your feature request related to a problem? Please describe.
When runnning satis build, and updating a package fails with 'Failed to update ...', Satis does not exit with a non-zero RC. This can cause errors to be missed.

Describe the solution you'd like
Exit with non-zero RC on failure.

Describe alternatives you've considered
N/A

Additional context
N/A