Revert "Proposed solution for issue #656 - "Default flag not working on tracks (subtitles, captions)""

This reverts commit 8735935b2232cc5c9ed027d2ae279259006df717.
Uncommented existing default track logic in addTextTrack function to allow default tracks to be shown appropriately.
Added setTimeout workaround so that exception is not thrown because of html5 tech issue.
Removed "default" attribute from player unit test so that track does not try to load extern during validation.