Load time optimisations

This branch makes some improvements to the application's load time (details in the commits).

The improvements to the load time (measured on a Tizen device, running the app in the web runtime) are as follows:

* Load time (from white screen to app visible) is 41% of original load time (measured using video)
* Load time (from fetch start to all JS execution finished, resources loaded etc.) is 44% of original load time (measured using performance.timing)
* Page show time (from fetch start to DOMContentLoaded end)  is 48% of original page show time (measured using performance.timing)

I also added a grunt build target to produce a set of files suitable for use with the SDK.