Merge pull request #75 from BBC-News/browsers-compatibility

[READY] Browsers compatibility
Using full secured credentials.
Running `npm run test-{remote,local}` according to the context.

- moving jshint to `npm run test-pre`
- enabling screen buffer to handle Firefox
- running `npm run test-remote` if there is no PR number
- running `npm run test-local` otherwise
Merge pull request #76 from oncletom/feature-76

Running SauceLabs on branch, locally otherwise