Add Expand All/Collapse All Button(s) to Agile Card views

[#1]

It'd be helpful to have an expand all / collapse all button for the card views. Right now, I have to expand or collapse each one at a time.

[#2]

This is important because the custom fields are only visible when the cards are expanded so I can't, for instance, see the points on an unexpanded card. this makes it very tedious to see how many points are in-flight at once.