--sauce CLI flag is broken

[anselmbradford]

At some point the Sauce Connect --sauce flag broke and doesn't work anymore. Fixing this issue should really address #885 as well.

Also, #887 and #886 are Sauce issues.

Current behavior

• Tests run with and without the --sauce flag do not run on Sauce, even with the SAUCE_USERNAME and SAUCE_ACCESS_KEY credentials set in .env.

Expected behavior

• Tests run with the --sauce=true flag set should attempt to run tests through a local running Sauce Connect tunnel. (In the past the behavior was also make this the default, so no --sauce flag at all would be equivalent to its value being true.)

Steps to replicate behavior

1. Set SAUCE_USERNAME and SAUCE_ACCESS_KEY credentials in .env and uncomment SAUCE_SELENIUM_URL.
2. Run gulp test:acceptance --sauce=true and note that there are no errors around Sauce connect not running and the tests run locally as if gulp test:acceptance --sauce=false were set.

[sebworks]

Fixed in #3040

[sebworks]

(In the past the behavior was also make this the default, so no --sauce flag at all would be equivalent to its value being true.)

I've modified the code to not default to Sauce because it does require setting .env variables and runs externally.