default: -p selenium
html_report: --format pretty --format html --out=features_report.html
bvt: --tags @test
browserstack : DRIVER=browserstack
testingbot: DRIVER=testingbot
poltergeist : DRIVER=poltergeist
selenium : DRIVER=selenium
appium_android : DRIVER=appium_android
appium_ios : DRIVER=appium_ios
sauce : DRIVER=sauce