#55 Celery parcel updating

* adds celery to project
* adds celery background task for updating parcels
* adds parcel calculation to creating of new geometries as well
* tests outstanding!!!

README.md

@@ -3,6 +3,14 @@ Konova is the successor of KSP. It's build using the python webframework Django,
 the database postgresql and the css library bootstrap as well as the icon package
 fontawesome for a modern look, following best practices from the industry.
 
+## Background processes
+Konova uses celery for background processing. To start the worker you need to run
+```shell
+$ celery -A konova worker -l INFO
+```
+More info can be found [here](https://docs.celeryproject.org/en/stable/getting-started/first-steps-with-celery.html#running-the-celery-worker-server).
+Redis must be installed.
+
 ## Technical documentation
 Technical documention is provided in the projects git wiki.