modified gmg to use plugin media_types and converted image media_type to new plugin style
removed CompatMediaManager() since all core media_types are classes
removed sniff_handler from Imange Media Manager class
fixed some typos and enabled media_type plugins in tests
converted ascii media_type to plugin
typo in image supported_filetypes
converted audio media_type to plugin
converted pdf media_type to plugin
converted stl media_type to plugin
converted video media_type to plugin
added a warning for old media types
Changing the information spat out while printing from media types->plugins

Previously it called even plugins media types.  Ha!

This commit sponsored by Jon Merkley.  Thank you!
Switch the import of the image media manager over to the new class

This helps resolve one of the remaining issues with the tests for the
media type pluginification.

This commit sponsored by Jeffrey Moe.  Thanks Jeff!  Lulzbot rocks!
Fix the last bit preventing all the unit tests from passing in media types->plugins

The last commit was also small, so Jeff Moe gets... two!  Two sponsored commits!
Ah ah ah. </count_voice>
Merge branch 'rodney757-media_plugins'

Conflicts:
	mediagoblin.ini
	mediagoblin/tests/test_mgoblin_app.ini
documenting the new media_type plugins and available hooks