Add force_width, force_height attributes to image

[fluffy-critter]

Expected Behavior

force_width should force an image to appear at the specified width even if it's larger than max_width or the image width.

Same for force_height respective to heights.

It should not cause the underlying image rendition to be scaled up past the original image size, however.

Context

Sometimes you just really want an image to be a particular size, such as in a thumbnail context.

[fluffy-critter]

Wait this is silly, we already have resize="stretch"

[fluffy-critter]

oh but that only works for external/static images