Let users display an image as a message


![jordans](https://cloud.githubusercontent.com/assets/747743/5037909/1726437a-6b59-11e4-9bbf-49c3dc6778b8.PNG)
If a user pastes in an image string (for example: http://4.bp.blogspot.com/-pqjGZvbJ2vw/UsE3u79xyEI/AAAAAAAAAvo/HxaD9DjPzvQ/s640/air-jordan-6-infa-red-retro.jpg), the image is shown in the message box.

If the message passes the regex for an image (with no spaces), an html image element is created, otherwise sanitize the string as before.

I added CSS to constrain the image.