Merge pull request #3461 from tinybug/patch-2

Update vube.py
[vube] Extract audio and categories
[xboxclips] Add new extractor
[nowness] Add support for cn URLs (Closes #3465)
Merge branch 'xboxclips' of https://github.com/pyed/youtube-dl into pyed-xboxclips
[xboxclips] PEP8 and extract more metadata
Merge branch 'pyed-xboxclips'
[arte] Do not filter formats when there are no videos of requested lang code (Closes #3433)
Merge pull request #3431 from sehaas/fm4

[fm4] Add new extractor
[fm4] Remove unused imports and minor changes
[orf] Move all ORF extractors in one place
Credit @sehaas for ORF FM4 extractor (#3431)
[downloader/common] Fix typo
[reverbnation] Make sure that the thumbnail url contain the protocol

They are protocol relative.
[reverbnation] Modernize test
[reverbnation] Simplify json download

We can directly get a json file instead of the jsonp.
[reverbnation] The 'uploader_id' field must be a string
[test/test_utils] Fix typo in method name
[facebook] Allow '?' before '#!' (fixes #3477)
[ard] Show error message for videos that are no longer available (#3422)