Update jquery.gridrotator.js

Added a Width to Height Ratio to the list of options. A 0.5 ratio would be used for an image that is twice as large as it's height. Default is 1 (square images).
Update jquery.gridrotator.js

Messed up my option name... It's heightToWidthRatio (Height/Width), not widthToHeightRatio (Width/Height)... Even tho I guess we could switch it around. I don't really mind. As long as we can use non-square thumbnails..!
Update jquery.gridrotator.js

I don't think it really matters, but might as well do it right..!
Merge pull request #3 from mbinette91/master

Options: Height to Width Ratio