Support multiple formats

The HTML5 version of the media player currently supports the provision of a single format for played files. Browsers such as Opera and Firefox do not support the MP4 format due to licensing issues:

[https://developer.mozilla.org/en-US/docs/HTML/Supported_media_formats#MP4_H.264_(AAC_or_MP3)](https://developer.mozilla.org/en-US/docs/HTML/Supported_media_formats#MP4_H.264_(AAC_or_MP3)

Also see this [test page](http://www.quirksmode.org/html5/tests/video.html) for an idea of support provided by your browser.

The player will use the HTML5 video tag if it is supported but support for different formats varies across browsers. This pull request adds the ability to send multiple formats as options based on support testing so the correct one will be chosen.