v0.2.1

- Updates to getEmbed method to include HTML5 as a fallback to Flash
and as a precursor to static image
- Updated TAS_Flex class to incorporate new getEmbed method and
therefore support embedded HTML5 executions within the Flex unit
- Bug fix for TAS_Custom and TAS_Flex that was preventing ads from
loading in Firefox. Had to do with Firefox rendering empty noscript
contents as undefined rather than an empty string.