Molmed/Checkqc: Remove Threading From The Web Service

The ProcessPoolExecutor functionality has been removed from the web service, basically reducing it to running things in a blocking fashion. The problem with the ProcessPoolExecutor was that it spawned a lot of threads that were left running and wouldn't terminate properly. The most straightforward way to fix it is, for now, to remove the threading. A Dockerfile has been added for running the web service in a container.