Added redis as backend dependency

backend/package.json

@@ -27,6 +27,7 @@
     "passport-github": "^1.1.0",
     "passport-local": "^1.0.0",
     "passport.socketio": "^3.7.0",
+    "redis": "^2.6.3",
     "request": "^2.74.0",
     "socket.io": "^1.5.0"
   }