Add an extractor for orf.at (closes #1346)

Make find_xpath_attr also accept numbers in the value
Fix orf.at extractor by adding file coding mark
Merge pull request #1347 from whydoubt/fix_orf_at

Fix orf.at extractor by adding file coding mark
[ign] extract videos from articles pages
[ign] update 1up extractor to work with the updated IGNIE
[youtube] update algo for length 86 (fixes #1349)
[youtube] update algo for length 84

Only appears sometimes, nearly identical to length 86.
release 2013.08.29
Add youtube keywords to the bash completion script
[youtube] Fix typo in the _VALID_URL for YoutubeFavouritesIE, it was intended to also match :ytfavourites
[youtube] update algo for length 86
release 2013.08.30
add support for "-f mp4" for YouTube
Merge remote-tracking branch 'upstream/master'