Minimum width/height

[tomjanssens]

We need to add a minimum height/width setting for attached images. They need to be big enough so fit nicely in our responsive design, Twitter, Facebook, etc.

Need to figure out if we can do this before upload or we process the picture first then showing a message and remove the image again.

Max resolution
Check for the max resolution, we're having issues with 300 DPI images. See https://stackoverflow.com/questions/14358524/is-there-a-way-when-uploading-images-jpeg-to-check-the-dpi