Min/max constraints for CMS dialog

This has bugged me for a long time. The $.ui dialog isn't that smart about its dimensions. I've added min/max settings, and stay within a ratio relative to the window size between those values (80% width/height).

Before (after resize): ![](https://api.monosnap.com/image/download?id=oG1QYqZ9jSVzQTgSUxMqOnIaM)

After: ![](https://api.monosnap.com/image/download?id=X6DJweo3Dhf7xpokOjIYZka0j)