Updated some paths on the e2e tests
Added a private SauceLabs config file for testing purpouses
FEATURE: Added the possibility to run the e2e tests on a saucelabs account.

How to use:

Create a credentials file "saucelabs.json" located inside the Gruntfile.js file.
A file "saucelabs.json.sample" is provided with the 3 basic params.

Once the file is completed with valid SauceLabs credentials, we can run our e2e tests on two modalities:

1. Local:
$ grunt test:e2e

2. On SauceLabs servers:
$ grunt protractor:saucelabs