Merge pull request #7 from j19sch/may2021-improvements

adds import instructions to exercise 4

improves api docs

pins some versions in requirements.txt

more falcon and Docker tweaks

fixes another falcon depcrecation

replaces falcon's deprecated API with App

Dockerile fixes

removes ToDo from extras README

Dockerfile update

changes exercise 5 to use log level info instead of debug

README and requirements.txt improvements

adds link to VS Code for debugging

renames teardown only next steps file

fixes jsonschema extra