refactor: backport new batching function

lib/constants.js

@@ -1,6 +1,13 @@
+const CASH_OUT_MINIMUM_AMOUNT_OF_CASSETTES = 2
+const CASH_OUT_MAXIMUM_AMOUNT_OF_CASSETTES = 4
+
 const anonymousCustomer = {
   uuid: '47ac1184-8102-11e7-9079-8f13a7117867',
   name: 'anonymous'
 }
 
-module.exports = {anonymousCustomer}
+module.exports = {
+  CASH_OUT_MINIMUM_AMOUNT_OF_CASSETTES,
+  CASH_OUT_MAXIMUM_AMOUNT_OF_CASSETTES,
+  anonymousCustomer
+}