[qa] Consistent calls to action

[aturon]

We sometimes use buttons, sometimes plain links. Sometimes images are the links. Let's work toward a consistent style (or couple of styles) for calls to action and apply it throughout.

[ashleygwilliams]

on this, i've made an effort to make every CTA a button. i think we should stick with this. (though if there are strong objections please do comment!)

[aturon]

I'm 👍 on buttons, but we may want to put some thought into avoiding the super wide buttons that show up in a few places (and feel a little awkward).