Change dev environment setup to use postgresql

- sqlite causes too many errors
- fix requirements file
- fixes for docker setup
- A lot of concurrency issues
- Bite the bullet, time to go!

docker/Dockerfile

@@ -101,7 +101,7 @@ RUN chown -R inventree:inventreegroup ${INVENTREE_HOME}/*
 USER inventree
 
 # Install InvenTree packages
-RUN pip3 install --no-cache-dir --disable-pip-version-check -r ${INVENTREE_HOME}/requirements.txt
+RUN pip3 install --user --no-cache-dir --disable-pip-version-check -r ${INVENTREE_HOME}/requirements.txt
 
 # Need to be running from within this directory
 WORKDIR ${INVENTREE_MNG_DIR}