Error in webapp after loading test fixtures

**Describe the bug**
Loading the test fixtues and running the web app results in a jinja exception.

**To Reproduce**
1) Start a clean GHC environment
2) Create a database and admin user
3) Serve the web app -> works
4) Stop the web app
5) Load test fixtures `python GeoHealthCheck/models.py load tests/data/fixtures.json`
6) Serve the web app -> Error:

```
jinja2.exceptions.UndefinedError

jinja2.exceptions.UndefinedError: 'dict object' has no attribute 'OSGeo:WFS3'
```

**Expected Behavior**
I expect GHC to *not* show an error report and to *do* show me the probes and checks configured in the test fixtures.

**Screenshots or Logfiles**
At the end of the error message:
```
File "GeoHealthCheck/templates/home.html", line 14, in root

File "/GeoHealthCheck/templates/layout.html", line 94, in root

File "/GeoHealthCheck/venv/lib/python3.7/site-packages/jinja2/environment.py", line 411, in getitem
return obj[argument]
jinja2.exceptions.UndefinedError: 'dict object' has no attribute 'OSGeo:WFS3'
```
**Context (please complete the following information):**
- OS: MacOS 10.14.6
- Browser:
- Browser Version
- Python Version 3.7
- GeoHealthCheck Version 0.8.0dev (commit: 61592f3a161b2ea66b8def6fbfb006ce9668eda8)

If running with Docker:
- not tested in docker

**Additional context**
No issues with running the tests.

Beginne mit GeoHealthCheck/models.py und dem Test-Fixture-Befehl, der tests/data/fixtures.json verwendet. Reproduziere den Fehler, indem du die Fixtures lädst und die Web-App bereitstellst, und untersuche dann templates/home.html und templates/layout.html rund um den gemeldeten Jinja-Traceback. Als erledigt gilt die Aufgabe, wenn die Web-App ohne Fehlerbericht geladen wird und die Probes und Checks aus den Fixtures anzeigt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.