Feature request: Add video license to output dict of Vimeo videos

[zhuyifei1999]

(Related ticket for YouTube: #8725)
There is no mentioning of video license in output dict of Vimeo videos:

>>> dl.extract_info('https://vimeo.com/157316669', download=False).keys()
WARNING: Parameter outtmpl is bytes, but should be a unicode string. Put  from __future__ import unicode_literals  at the top of your code file or consider switching to Python 3.x.
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.03.01
[debug] Python version 2.7.6 - Linux-3.19.0-49-generic-x86_64-with-Ubuntu-14.04-trusty
[debug] exe versions: avconv 9.18-6, avprobe 9.18-6
[debug] Proxy map: {}
[vimeo] 157316669: Downloading webpage
[vimeo] 157316669: Extracting information
[vimeo] 157316669: Downloading webpage
[vimeo] 157316669: Downloading JSON metadata
[vimeo] 157316669: Downloading m3u8 information
[u'display_id', u'upload_date', u'protocol', u'description', u'extractor', u'requested_subtitles', u'format', u'tbr', u'height', u'like_count', u'uploader', u'duration', u'format_id', u'id', u'subtitles', u'view_count', u'playlist', u'thumbnails', u'fps', u'title', u'url', u'extractor_key', u'http_headers', u'ext', u'uploader_id', u'width', u'comment_count', u'playlist_index', u'webpage_url', u'formats', u'thumbnail', u'webpage_url_basename']

In a browser, the license is shown in the popup of "more" link beside the uploader.

Why is this needed? It is usually necessary to know the license in order to comply with the terms (see downstream bug).

[dstftw]

Do you have any example URL with non CC licensed videos?

[zhuyifei1999]

This one on front page seems to have no license.
There are examples for Creative Commons and Public Domain videos on https://vimeo.com/creativecommons

[JeanFred]

I had started implementing this ages ago in JeanFred/youtube-dl@423587d ; I have no clue whether this is even remotely rebase-able, but let me know :)

[legoktm]

@dstftw fixed this with c38a67b. Thanks!