Add production config

This is copied from alphagov-deployment. These files don't contain
any secrets, but they import from a file called `environment.py`
which does.

backdrop/read/config/production.py

@@ -0,0 +1,8 @@
+import os
+
+DATABASE_NAME = "backdrop"
+MONGO_HOSTS = ['performance-mongo-1', 'performance-mongo-2', 'performance-mongo-3']
+MONGO_PORT = 27017
+LOG_LEVEL = "INFO"
+
+from environment import *

backdrop/transformers/config/production.py

@@ -0,0 +1 @@
+from environment import *

backdrop/write/config/production.py

@@ -0,0 +1,15 @@
+DATABASE_NAME = "backdrop"
+MONGO_HOSTS = ['performance-mongo-1', 'performance-mongo-2', 'performance-mongo-3']
+MONGO_PORT = 27017
+LOG_LEVEL = "INFO"
+DATA_SET_UPLOAD_FORMAT = {
+    "ithc_excel": "excel",
+}
+DATA_SET_UPLOAD_FILTERS = {
+    "ithc_excel": [
+        "backdrop.core.upload.filters.first_sheet_filter",
+    ],
+}
+SESSION_COOKIE_SECURE=True
+
+from environment import *