Remove trailing slash from api paths

A proxy refused to include trailing slashes, and so they have been removed.

Resolves: GREG-76

greg/tests/api/test_health.py

@@ -3,6 +3,6 @@ import pytest
 
 @pytest.mark.django_db
 def test_health_says_ok(client):
-    response = client.get("/api/health/")
+    response = client.get("/api/health")
     assert response.content == b"OK"
     assert response.status_code == 200