Relocate the cordova polyfills in a dedicated file, and load it immediately
after the cordova.js load, so the polyfills are available as soon as
possible, when necessary.

Add a cordova polyfill for cordova.define, so we can blithely continue
without the plugins, in so far as the lack of their functionality allows.

(This enables us to continue without the FileViewerPlugin, for instance,
without any accommodation within the plugin, itself.)
Merge pull request #31 from SpiderOak/gather-cordova-polyfills

Relocate the cordova polyfills in a dedicated file, and load it immediately...