[test_download] Improve playlist handling
[ted] Remove md5sum from test

This failed multiple times, and the md5sum is not that important anyways.
[utils] Modernize tests
[dailymotion] Correct test case
[nhl] Modernize
Move playlist tests to extractors.

From now on, test_download will run these tests. That means we benefit not only from the networking setup in there, but also from the other tests (for example test_all_urls to find problems with _VALID_URLs).
fix up imports
Merge remote-tracking branch 'origin/master'
[extractor/common] Modernize
[veehd] Modernize
release 2014.08.28