Add version history to app details pages

Helps #1111 (closed)

Here are some screenshots: (The orange rectangle is the focused widget when using keyboard navigation.) (In this one the latest release doesn't have a description.) (For this app no release history is available.) (Apparently some apps have very detailed descriptions of releases, and perhaps there should be some truncation, but that can be a future improvement rather than block this MR.)

cc @bertob