Reportback modal cropping

*Links up the cropping functionality into the image upload modal and populates the main reportback form with the cropping coordinates.

*Moved cropping interface styles to the crop modal sass.

@weerd 

Is there a reason why this is *required* here and not up top? Isn't it all getting compiled together anyhoo, so might as well just require it at top with everything else... unless I'm missing something?