JMicrodata library and tests

JMicrodata class usage documentation https://gist.github.com/PAlexcom/6339949

* test/usage examples in __tests/unit/suites/libraries/joomla/microdata/microdata.php__
* the __libraries/joomla/microdata/types.json__ file was generated with the __https://github.com/PAlexcom/Spider4Schema__ crawler

Joomla Tracker: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31989&start=0