Evaluate integration of Saucelabs in order to test cross-browser compatibility on commit

[evilaliv3]

It would be valuable to implement an integration with SauceLabs in order to perform end-to-end testing in the cloud testing against cross-browser compatibility.

Given the fact that sjcl already implement the possibility to test in the browser(https://github.com/bitwiseshiftleft/sjcl/tree/master/browserTest) it would be possibile to simply run existing tests on all the targeted browser by means of:

1. a simple webserver pointed to directory browserTest
2. run grunt + mocha + grunt-saucelabs as done in https://github.com/dchest/scrypt-async-js/blob/master/Gruntfile.js

in addition using grunt-instanbul it would be possible to instruct the code and collect the code coverage obtaining an output like the one you see here in the README visualization https://github.com/dchest/scrypt-async-js