Move registerServiceWorker, notification to utils

- utils is a new directory under ./src/ holding misc modules that don't seem to
  fit anywhere else.
- createStore was excluded from utils since the store is a core part of our
  react/redux app, and so it does make sense as a standalone module in the root
  ./src/ directory
- Also fixed #37 unnecessary yield undefined.

src/index.tsx

@@ -9,7 +9,7 @@ import { Store } from 'redux'
 import ApplicationContainer from './containers/ApplicationContainer'
 import createStore from './createStore'
 import { IState } from './reducers/states'
-import registerServiceWorker from './registerServiceWorker'
+import registerServiceWorker from './utils/registerServiceWorker'
 
 import './styles/index.css'
 

src/sagas/index.ts

@@ -6,7 +6,7 @@ import { Context, interrupt, runInContext } from '../slang'
 
 import * as actions from '../actions'
 import * as actionTypes from '../actions/actionTypes'
-import { showSuccessMessage, showWarningMessage } from '../notification'
+import { showSuccessMessage, showWarningMessage } from '../utils/notification'
 
 function* evalCode(code: string, context: Context) {
   const { result, interrupted } = yield race({
@@ -53,8 +53,6 @@ function* interpreterSaga(): SagaIterator {
       yield put(actions.clearContext())
       yield put(actions.clearReplOutput())
       yield call(showSuccessMessage, `Switched to Source \xa7${newChapter}`)
-    } else {
-      yield undefined
     }
   })
 }