Reconfigure travis/sauce to work better with forks and pull requests

Dont secure sauce credentials, they aren't that secret.
Use travis builtin sauce_connect addon.
Use environmental varialbes to store user/access_key.  The SaucelabsFactory class from Behat will use these environmental variables in its own configuration.
Manually install sauce_connect

Because sauce_connect is disabled by travis (see:
travis-ci issue 2135) we have to manually
install it ourselfes.
Always load sauce_connect

Load sauce connect no matter what since we are always setting the environmental variables anyway.
remove extra before_script section
Curl redirect in travis.yml

Allow curl to follow redirects since github moves their gist domain around.
Merge pull request #565 from jrjohnson/reconfiguretravis

Reconfigure travis/sauce