move map as a supdirectory of challenges

common/app/routes/challenges/redux/index.js

@@ -1,3 +1,6 @@
 export actions from './actions';
 export reducer from './reducer';
 export types from './types';
+
+import fetchChallengesSaga from './fetch-challenges-saga';
+export const sagas = [ fetchChallengesSaga ];