Adds a simple sc-phantom wrapper command.

This just looks for phantomjs/test_runner.js in the /sproutcore target,
then invokes it under PhantomJS. PhantomJS is assumed to be in the PATH.

All arguments are simply passed through to PhantomJS. The ability to pass
through arguments like this was not present in thor 0.14, so I bumped the
version requirement as well.
Merge pull request #103 from FernCreek/patch/fairbanksg/sc-phantom

Adds a simple sc-phantom wrapper command.