have app version report use build_id first (new!)

- use caching to make build_id => version number lookup fast
- add simple test
add another appversion pattern

and refactor to add doctest
improve app status report to be more explicit

- have a hover show where exactly the build version came from
- put build versions in nice little html labels
- give an affordance showing that xform versions are lower bounds not
  absolute
preemptively fix merge conflict
Merge pull request #3537 from dimagi/app-version-report

Improve Application Status report