Ensure Docker client uses exit codes when errors occur

This patchset essentially ensures that the Docker client actually exits with error codes if an error is encountered.

Docker-DCO-1.1-Signed-off-by: Aleksa Sarai <cyphar@cyphar.com> (github: cyphar)

/cc @shykes @vieux @crosbymichael
Are you sure you can enforce this for everything because if you miss one the user will get a panic and not see the error message?