Example how to store things when the browser is in offline mode.
- http://blog.fox21.at/2015/10/15/html5-application-cache.html
- http://pablotron.org/software/persist-js/
- https://github.com/jeremydurham/persist-js
- http://stackoverflow.com/questions/2786303/offline-mode-app-in-a-html5-browser-possible
- http://www.html5rocks.com/en/features/storage
- http://www.html5rocks.com/en/tutorials/appcache/beginner/
- http://www.w3schools.com/HTML/html5_webstorage.asp
- http://fortuito.us/diveintohtml5/offline.html