Support image resizing syntax in editor preview

[durden]

Some variants of markdown allow for resizing an image. Maybe we should support this as well? I think github supports it, see this gist:

https://gist.github.com/uupaa/f77d2bcf4dc7a294d109

[durden]

@prtkgpt You were trying this recently in the editor. Any thoughts? What syntax were you trying?

[prtkgpt]

@durden I tried these two at the end of (image link =800x600) and (image link =500x)

http://stackoverflow.com/questions/14675913/how-to-change-image-size-markdown

[paulocheque]

html is supported, example:

<img src="http://fc01.deviantart.net/fs70/i/2012/173/a/0/circle__plain__by_treisaran-d54fnp6.png" width="40" height="60" />