Slow tests (#4435)

* Add integration for django-slowtest

* Sample test improvement

- Reduces test from 0.7s to 0.2s

* Run CI tests with slowreport

* Fix requirements file

* Fix test command

* Fix bulk_create in unit tests

* Remove bulk_create entirely

* remove another bulk_create call

* Reduce long test from ~1000 seconds to ~1 second

tasks.py

@@ -559,7 +559,7 @@ def test(c, disable_pty=False):
     pty = not disable_pty
 
     # Run coverage tests
-    manage(c, 'test', pty=pty)
+    manage(c, 'test --slowreport', pty=pty)
 
 
 @task(help={'dev': 'Set up development environment at the end'})