Got protractor e2e tests running
Converted e2e tests from casper.js to protractor

Converted all of the end-to-end tests from casper.js to protractor. To
run them locally, do the following from the root AngularFire directory:
./node_modules/protractor/bin/webdriver-manager start
python -m SimpleHTTPServer 3030
grunt protractor OR grunt test
Got protractor tests running through grunt and also cleaned up Gruntfile
Updated README so users can now run protractor tests
Updated README with updated grunt instructions
Adding SauceLabs integrations

Testing Travis CI build
Changing port number and adding server to grunt travis command
Trying another Travis CI build
Another Travis CI build with longer timeouts
Yet another Travis CI build

Failing protractor tests should now fail the build
Trying travis again
Decreasing sleep time and using new SauceLabs key

I accidentally previously pushed with our Sauce Labs access key in
plain text. I removed this old key and generated a new one and
encrypted it.
Cleaned up code now that everything is working
Updated README instructions and grunt install task
Merge pull request #316 from firebase/protractor_e2e_tests

Protractor e2e tests