youtube-dl: Updated to v2013.09.07

Changes since 2013.09.06.1:

  $ git algd 2013.09.06.1..2013.09.07
  * 8f36258 - release 2013.09.07
  *   a27a247 - Merge branch 'master' of github.com:rg3/youtube-dl
  |\
  | * a713054 - [generic] If the url doesn't specify the protocol, then try to extract prepending 'http://'
  | * a490fda - [daylimotion] accept embed urls (fixes #1386)
  | * 7e77275 - Add an extractor for Metacritic
  | * e3ea479 - [youtube] Fix some issues with the detection of playlist/channel urls (reported in #1374)
  | * faab1d3 - [youtube] Fix detection of feeds urls (fixes #1294)
  * 8851a57 - Fix add-versions

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