remove startup dependency on s3 settings

services/track-changes/app/coffee/MongoAWS.coffee

@@ -9,12 +9,11 @@ zlib = require "zlib"
 
 DAYS = 24 * 3600 * 1000 # one day in milliseconds
 
-AWS_CONFIG = {
-	accessKeyId: settings.trackchanges.s3.key
-	secretAccessKey: settings.trackchanges.s3.secret
-}
-
 createStream = (streamConstructor, project_id, doc_id, pack_id) ->
+	AWS_CONFIG =
+		accessKeyId: settings.trackchanges.s3.key
+		secretAccessKey: settings.trackchanges.s3.secret
+
 	return streamConstructor new AWS.S3(AWS_CONFIG), {
 		"Bucket": settings.trackchanges.stores.doc_history,
 		"Key": project_id+"/changes-"+doc_id+"/pack-"+pack_id