Django upgrade to 2.2.11 ( security recommendation from github)

[id2359]

Follow best practice as outlined in Django docs to upgrade

[jithendralal]

[INFO:2020-02-10 14:27:22,330:apps.py:14:ready] running RDRFConfig.ready ...
SystemCheckError: System check identified some issues:

ERRORS:
?: (urls.E007) The custom handler404 view 'rdrf.urls.handler404' does not take the correct number of arguments (request, exception).

[jithendralal]

2ba6729 - 404 handler modified to match the new django version
build on Travis failed:
AssertionError: Database queries to 'clinical' are not allowed in this test. Add 'clinical' to rdrf.testing.unit.tests.ClinicalDataTestCase.databases to ensure proper test isolation and silence this failure.

d3d49ef - class attribute 'databases' added to tests
build on Travis failed:
SAWarning: The GenericFunction 'array_agg' is already registered and is going to be overriden.

7f2c650 - version bumped up sqlalchemy-utils==0.34.0
build on Travis failed:
There is 1 other session using the database. (session not closed when using a new export zip)

Similar issue: https://github.com/muccg/mtm/issues/316

Tried downgrading SQLAlchemy==1.2.5 and SQLAlchemy-Utils==0.33.1
as suggested in this issue:
fastmonkeys/stellar#77
but
docker exec -it rdrf_runservertest_1 /app/docker-entrypoint.sh bash
pip freeze
shows
SQLAlchemy==1.3.12
SQLAlchemy-Utils==0.34.0
cleaned everything and built again
SQLAlchemy==1.2.5
SQLAlchemy-Utils==0.33.1

74c55e3 - Added logging to terrain and utils and pushed the changes to see the sequence of processes, during the build on travis.

[jithendralal]

50126ab - url in stellar.yaml config files modified (template1 was removed from url) to test the effect

local build failed:
rdrf.services.io.content.export_import.exceptions.ImportError: Schema difference detected between your registry and the export file. App(s) with different schema: auth

travis build failed:
database "webapp" does not exist