fix: code runner (#239)

- make code runner and editor responsive
- replace iframe code runner with react-runner

Author: Yilun-Sun

package-lock.json

@@ -83,6 +83,7 @@
     "react-router": "^3.0.0",
     "react-router-redux": "~4.0.7",
     "react-router-scroll": "~0.4.1",
+    "react-runner": "^1.0.3",
     "recharts": "^2.3.1",
     "redux": "4.0.0",
     "redux-thunk": "^2.3.0",