Add images vertical, gruntfile, test

Hey there,

I'm a MSFT coder in developer evangelism.  I wanted to do some work with the Bing API and quickly realized there didn't seem to be an official Node client.  Your unofficial client looked the most promising (well-structured, easy to test thanks to the options, light-weight), so I decided to fork it and add the images vertical (which is what I needed), and then add some grunt tasks and a basic test. 

I hope this is helpful, let me know if there are other changes you were making or needed and I'll see what I can do to help (unofficially).

P.S. I love your avatar pic :)