rg3/youtube-dl — pull request #1223 by daureg (2013-08-10 00:16:44+00:00)
Title: fix #1213 by returning an empty dictionary if there is no subtitle.

Make ```_get_available_subtitles()``` always return a dictionary, but empty if there is no available subtitles. In this case, use a member variable to keep track of the error message (either a failure to get information from ```video.google.com/timedtext``` or the fact that there is actually no available subtitles).