Rename config to options
Rename runner-/driverArgs to runner-/driverOptions
Fill in driverOptions defaults
Rename create / end to start / stop
Protect private members
Provide updateCapabilities on driver
Merge driverOptions.args
Manage browsers and capabilities
Set args after we've got the port
Wrap all driver option within --driver-option-*
Read env variables for SAUCE_USER / SAUCE_ACCESS_KEY
Proper child process error handling
Properly handle process.exit