Rename Gulpfile.js -> gulpfile.js because i hate capitals

And also https://github.com/gulpjs/gulp/blob/master/docs/getting-started.md#3-create-a-gulpfilejs-at-the-root-of-your-project
Merge pull request #243 from putaindecode/website.gulpfile

Rename Gulpfile.js -> gulpfile.js because i hate capitals