add tests for mysql and postgress, some fixes for those backends

tests/settings.py

@@ -1,5 +1,11 @@
 import os
 
-os.environ['TEST_DATABASE_URLS'] = "sqlite:///test.db"
+import databases
 
+assert "DATABASE_URL" in os.environ, "DATABASE_URL is not set."
+
+DATABASE_URL = os.environ['DATABASE_URL']
+database_url = databases.DatabaseURL(DATABASE_URL)
+if database_url.scheme == "postgresql+aiopg":  # pragma no cover
+    DATABASE_URL = str(database_url.replace(driver=None))
 DATABASE_URL = os.getenv("DATABASE_URL", "sqlite:///test.db")