Create reducer for controls

src/reducers/controls.js

@@ -0,0 +1,14 @@
+const Controls = (state = {
+  color: null,
+}, action) => {
+  switch (action.type) {
+  case "color changed":
+    return Object.assign({}, state, {
+      color: action.data,
+    });
+  default:
+    return state;
+  }
+};
+
+export default Controls;

src/reducers/index.js

@@ -4,11 +4,13 @@ import thunk from "redux-thunk";
 
 import initialize from "./initialize";
 import cells from "./cells";
+import controls from "./controls";
 import selectedMetadata from "./selectedMetadata";
 
 const Reducer = combineReducers({
   initialize,
   cells,
+  controls,
   selectedMetadata,
 })