Use require('system').args instead of phantom.args

I realize this changed is warned against in the comments that I removed, but `phantom.args` is [http://phantomjs.org/api/phantom/property/args.html](depreciated) and as far as I can tell, has been removed completely in PhantomJS 2.0.0 (development).

Moving this over to `require('system').args` works without issue for me. Note that I am running `phantomjs` directly and [http://casperjs.readthedocs.org/en/latest/faq.html#can-i-use-casperjs-without-using-the-casperjs-executable](including CasperJS within the script).