Added new type definition and test for redux-immutable

redux-immutable/redux-immutable-test.ts

@@ -0,0 +1,6 @@
+import { combineReducers } from 'redux-immutable';
+import { routerReducer } from 'react-router-redux';
+
+combineReducers({
+   routing: routerReducer
+});

redux-immutable/redux-immutable.d.ts

@@ -0,0 +1,3 @@
+declare module "redux-immutable" {
+    export function combineReducers(reducers : Object): Object;
+}