OSMF SVN

Add ExcludeClass metadata to classes that must be public, but whose API we don't want to expose to framework clients.

Add sample plugin and app to demonstrate use of resource-level metadata to allow a plugin to create media for a resource that would otherwise be handled by a core MediaInfo.

Fix ListenerProxyElement unit tests.

Update example that uses proxy to trace all events to use ListenerProxyElement.

Update terminology in readme file.

PARB feedback: Rename playhead to currentTime, bytesDownloaded to bytesLoaded. Affects traits, MediaPlayer, and events. Updated dependent unit tests and sample apps.

This is an empty revision for padding.

PARB feedback: Refactor MediaPlayerState to convert constants to strings. Remove all other methods. Update dependent code.

PARB feedback: Refactor StreamType to convert constants to strings. Remove all other methods. Update dependent code.

PARB feedback: Refactor ScaleMode to convert constants to strings. Move utility function into dedicated utility class (ScaleModeUtils). Remove all other methods. Update dependent code.