OSMF SVN

Introduce priority scheme into NetClient's addHandler method. This allows us to keep NetStreamPlayTrait's listeners for Play.Stop and Play.Complete in sync, in terms of priorities. Also reordered the adding of the NetStreamTimeTrait and NetStreamPlayTrait so that the former is added first. This fixes a bug where the NSPlayTrait would trigger the onMetadata callback before the NSTimeTrait was added, thus preventing the latter from ever catching the actual duration.