Return parsed json from redis cache (#142)

src/cache/redis.js

@@ -24,7 +24,7 @@ try {
       get(key, callback) {
         console.log(`redis-dummy get: ${key}`); // eslint-disable-line no-console
         const hit = mockCache[key];
-        return Promise.resolve().then(callback(null, hit));
+        return Promise.resolve().then(callback(null, JSON.parse(hit)));
       },
       set(key, json, callback) {
         console.log(`redis-dummy set: ${key}`); // eslint-disable-line no-console