fix exports for mocking

Author: bdwain

src/index.js

@@ -1,5 +1,6 @@
 import c from './combine-reducers';
 import m from './merge-child-reducers';
 
-export const combineReducers = c;
-export const mergeChildReducers = m;
+//by exporting functions, these are able to be spied on
+export function combineReducers(...args){return c(...args);}
+export function mergeChildReducers(...args){return m(...args);}