Add API methods for aspectRatio, minSize & maxSize

[guidobouman]

Example:

api.setAspectRatio(crop.width / crop.height);
api.setMinSize([crop.width, crop.height]);

[icreatestuff]

I had a sneak peak at the source code and found a 'setOptions' method that looks like it'll take any of the initialization options and override them.

For example:

api.setOptions({aspectRatio: 1});

[morenoh149]

yep I used that to declare I only wanted north and south handles. I thought the default 8 handle setup was dated and ugly

[guidobouman]

Ended up using that same method. =]