v1.7.8
chore(*): update minimum Yarn version, do some Yarn-related cleanups
chore(saucelabs): remove `SL_Safari` from browser list
chore(travis): suppress verbose log output and allow error logging
chore(travis): clean up browserstack/saucelabs scripts
build(travis): gracefully shut down the sauce connect tunnel after the tests are done running
chore(ci): fix location of print logs from wait_for_browser_provider