Moved class into seperate file, added ability to crop images

I created a wraith class and moved it into lib.  Made images crop down so there isn't so much white space.  PhantomJS seems to have a problem with window.innerHeight, so I picked 1500px as the default height, but if the window is bigger, it will just expand.  

New dependency on Gem image_size.

![myonotz](https://f.cloud.github.com/assets/1492067/905819/1be79138-fc52-11e2-9ab4-77e939a3f370.jpg)