[Enhancement] Swappable Packages (#216)

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#216
Reviewed-by: liambrydon <lbry121@aucklanduni.ac.nz>
Reviewed-by: Tobias O <tobias.olenyi@envipath.com>

envipath/settings.py

@@ -49,9 +49,23 @@ INSTALLED_APPS = [
     "oauth2_provider",
     # Custom
     "epdb",
-    "migration",
+    # "migration",
 ]
 
+TENANT = os.environ.get("TENANT", "public")
+
+if TENANT != "public":
+    INSTALLED_APPS.append(TENANT)
+
+EPDB_PACKAGE_MODEL = os.environ.get("EPDB_PACKAGE_MODEL", "epdb.Package")
+
+
+def GET_PACKAGE_MODEL():
+    from django.apps import apps
+
+    return apps.get_model(EPDB_PACKAGE_MODEL)
+
+
 AUTHENTICATION_BACKENDS = [
     "django.contrib.auth.backends.ModelBackend",
 ]