[youtube:playlist] Fix mixes extraction (fixes #2444)
[normalboots] Fix video url extraction
[normalboots] Modernize and simplify
[youtube] Fix mix video regex

Attributes' order in <li> is arbitrary and changes every time playlist
page is fetched, so we can't rely on `data-index` to be before
`data-video-username`.
[zdf] Fix podcast extraction and use unicode literals (Closes #2446)
release 2014.02.24
[iprima] Clean up a little bit
[iprima] Add support for -WEB URLs (Closes #2449)
[iprima] Add missing `)`
[nbc] Modernize
[academicearth] Fix extraction

The courses seems to be no longer available, changed the test to a playlist.
[academicearth] Remove debug print
[cinemassacre] Fix extraction

Now we download over http, we don't need rtmpdump.
[cinemassacre] Modernize
[novamov] Improve _VALID_URL
[novamov] Generalize extractor
[nowvideo] Rewrite based on novamov extractor
[podomatic] Use unicode_literals
[generic] Add support for nowvideo embedded videos
[veoh] Allow to download videos with age protection (fixes #2455)