I followed the same convention used for selenium:
   - `-s` - use selenium server to run test
   - `-r` - define URL of selenium server

In the case for sauce labs:
   - `-sauce-labs` - use sauce labs to run test
   - `-sauce-labs-server` - define URL of sauce labs server

If anything, I can probably make the command line options less verbose (possibly use the prefix `sl` or `sauce` instead of `sauce-labs`)