Improve test data organization and update correspoding conftests

- Put test data for each content type into separate directories
- Makes config.yml for docker and local host consistent
  - Prepending tests to /data in sample_config.yml makes application
    run on local host using test data
  - Allows mounting separate volume for each content type in docker-compose
- Ignore gitignore to only add tests content, not generated models or embeddings

.gitignore

@@ -1,7 +1,8 @@
 __pycache__
 .DS_Store
 .emacs.desktop*
-tests/data/.*
+tests/data/models
+tests/data/embeddings
 src/.data
 .vscode
 *.gz