[brightcove] Support videos that only provide flv versions (fixes #1504)

Moved the test from generic.py to brightcove.py
[brightcove] Use direct url for the tests

The test_all_urls.py test failed because BrightcoveIE doesn't match them.
[RTLnowIE] Add support for http://rtlnitronow.de
[RTLnowIE] Clean video title

The title of some videos has the following format:
Series - Episode | Series online schauen bei ... NOW
[youtube] Fix 83 signature (Closes #1511)
Merge remote-tracking branch 'rzhxeo/RTL'
Merge remote-tracking branch 'rzhxeo/RTL_T'
Don't embed subtitles if the list is empty or the field is not set (fixes #1510)
Remove youtube_genalgo (#1515)

With the automatic signature extraction, this script has become superfluous now
Merge branch 'master' of github.com:rg3/youtube-dl
Don't fail if the video thumbnail couldn't be downloaded (fixes #1516)

Just report a warning
[youtube] update description of test
[youtube] Set the thumbnail to None if it can't be extracted
[youtube] Add hlsvp to the error message if it can't be found and remove the live stream test

It's no longer available, other olympics streams have the same problem.