[FEED] - Delayed postProcessing of feeds if not visible

- Leveraged the feed element to store results of requests first to allow for delayed postProcessing
- Utilized the media player loading icon to display some sort of notification to users when the feed is working
- Introduced element level bindings with self removing eventListeners to not pollute the DOM needlessly.
- Cleaned up the demo feed in the tabbed interface example
- Introduced CSS based striping for some of the feed rendering
@nschonni , this was simply for the demo, since it was really bound by the way the content was laid out. Now that you bring it up I agree that it is probably better to incorporate into a class for better styling flexibility, since people will more than likely want the same visual available. I will adjust for after I can land a suitable and appropriate class name for it. Thanks.