Removing need to add PhantomJS to the PATH

We use your gem to run jasmine under phantomjs very successfully. The only pain point is the need to add phantomjs to the path. This is a problem especially when the version we want to use changes. We use the gem "phantomjs" from https://github.com/colszowka/phantomjs-gem to automatically download phantomjs and to use the correct version when starting a process. I have added the same gem to this project so you no longer need to add phantomjs to the PATH.