gulpjs/gulp — pull request #530 by borisguery (2014-06-13 12:25:52+00:00)
Title: Add usage with -h|--help flag

As advised by the [GNU coding standard](http://www.gnu.org/prep/standards/standards.html#g_t_002d_002dhelp), add some usage with `-h|--help` flag.

It got me crazy to have to go the website documentation to just remember the option to specify a custom `gulpfile.js`