Add ability to filter side cards to only show work items not estimated yet

[deadlydog]

It would be awesome if there was a checkbox or something that we could use to toggle only seeing work item cards that do not currently have Story Points assigned to them. Often times we end up with 30+ cards on the left side of the screen, where only a handful of them don't have estimates. We then have to hunt for the ones that we still need to estimate on. It would be great if we could easily hide cards (or grey them out so they are not as noticeable) that have Story Points assigned to them already.

[wislerd]

This would be amazingly helpful!