Option to skip cropping on MiniMagick#resize_to_fill

[etherbob]

Would you be amenable to a pull request that adds a crop: true parameter to MiniMagick#resize_to_fill that would then skip the cropping step when set to false?

We have a use case for calling resize("#{width}x#{height}^") and this seems like the logical place.

[janko]

Yes, that sounds reasonable 👍