Cordova example should have runtime detection for importing the correct cordova js file

The steps to replace CORDOVA_SCRIPT (see below) should have runtime detection and automatic usage of the correct .js for the platform.

<!-- Cordova script will be replaced with appropriate version at build time -->
<script type="text/javascript" src="CORDOVA_SCRIPT"></script>

We need to determine a good property to switch on, or alternatively use useragent for this (although that might not be ideal).