[beeg] Add support for feed page extraction

[BMitrovic17]

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• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like this: [x])
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Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2018.12.03. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2018.12.03

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

Add the -v flag to your command line you run youtube-dl with (youtube-dl -v <your command line>), copy the whole output and insert it here. It should look similar to one below (replace it with your log inserted between triple ```):

λ youtube-dl -v https://beeg.com/people/KyliePage
[debug] System config: []
[debug] User config: [u'-o', u'g:/%(title)s_%(id)s.%(ext)s', u'--merge-output-format', u'mkv']
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'https://beeg.com/people/KyliePage']
[debug] Encodings: locale cp1252, fs mbcs, out cp437, pref cp1252
[debug] youtube-dl version 2018.12.03
[debug] Python version 2.7.14 (CPython) - Windows-10-10.0.17763
[debug] exe versions: ffmpeg N-92374-gd96ae9d5ea, ffprobe N-92374-gd96ae9d5ea
[debug] Proxy map: {}
[generic] KyliePage: Requesting header
WARNING: Falling back on generic information extractor.
[generic] KyliePage: Downloading webpage
[generic] KyliePage: Extracting information
ERROR: Unsupported URL: https://beeg.com/people/KyliePage
Traceback (most recent call last):
  File "c:\python27\lib\site-packages\youtube_dl\extractor\generic.py", line 2339, in _real_extract
    doc = compat_etree_fromstring(webpage.encode('utf-8'))
  File "c:\python27\lib\site-packages\youtube_dl\compat.py", line 2542, in compat_etree_fromstring
    doc = _XML(text, parser=etree.XMLParser(target=_TreeBuilder(element_factory=_element_factory)))
  File "c:\python27\lib\site-packages\youtube_dl\compat.py", line 2531, in _XML
    parser.feed(text)
  File "c:\python27\lib\xml\etree\ElementTree.py", line 1659, in feed
    self._raiseerror(v)
  File "c:\python27\lib\xml\etree\ElementTree.py", line 1523, in _raiseerror
    raise err
ParseError: syntax error: line 1, column 0
Traceback (most recent call last):
  File "c:\python27\lib\site-packages\youtube_dl\YoutubeDL.py", line 792, in extract_info
    ie_result = ie.extract(url)
  File "c:\python27\lib\site-packages\youtube_dl\extractor\common.py", line 508, in extract
    ie_result = self._real_extract(url)
  File "c:\python27\lib\site-packages\youtube_dl\extractor\generic.py", line 3318, in _real_extract
    raise UnsupportedError(url)
UnsupportedError: Unsupported URL: https://beeg.com/people/KyliePage

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Not long ago beeg.com did a redesign of their website. Now we have ability to filter per actress/actor among other things.

Would be nice to be able to grab all the videos from the feed.

https://beeg.com/people/KyliePage
https://beeg.com/tag/milf

Unfortunately their Channel selection doesn't indicate it is one via url. So we'd need to parse HTML to be able to identify that it is one.
https://beeg.com/BigTitsAtSchool