Load time optimisations

This branch includes various optimisations (detailed in the commits) to improve the load speed of the webapps-sweetspot app.

It also adds a grunt build to make it easy to deploy the application to a Tizen device over sdb.

When loading the app as a Tizen package in the wrt, the improvements (depending on how you measure it and your hardware) are:

* Overall load time is 80% of the unoptimised time (measured using performance.timing)
* Overall load time is 62% of the unoptimised time (measured using video)
* Time to show the app (i.e. load the HTML and display it) is 30% of the unoptimised time (measured using performance.timing)