TypeError: _wait_until_connectable() got an unexpected keyword argument 'timeout'

Selenium introduced a timeout parameter in the FirefoxBinary class, and since sst's FirefoxBinary overriding class doesn't have it, code using sst explodes with:

TypeError: _wait_until_connectable() got an unexpected keyword argument 'timeout'

A simple interim fix is to add the timeout parameter to _wait_until_connectable. But maybe we should revisit sst's FirefoxBinary class and see if the upstream problems which prompted its creation are now gone (maybe the very timeout behavior was implemented because of that).