[Tracker] Support for Extracting CC License Metadata

[Jason Kivlighn <jkivlighn gmail com>]

Hi,

I'd like to write/extend extractors to support indexing CC license
metadata.  Creative Commons has recommendations for how to embed this
information in various file formats at
http://creativecommons.org/technology/usingmarkup.

I'd like to follow these recommendations and add support for the formats
listed in that page.

Does this sound do-able?  I'm considering it for a Google SoC project
under Creative Commons (Frankly, I'm not sure if that would work,
though, since I'd be contributing code here).

Cheers,
Jason Kivlighn