[test/test_unicode_literals] Remove duplicated imports
Use flake8 instead of pyflakes and pep8

It combines both tools
Move flake8 configuration to setup.cfg

It will be used when calling flake8 from any directory in the project
flake8: Add more ignored files

* setup.py: the '__version__' variable is not defined in the script, it is loadded from youtube_dl/version.py
* devscripts/buildserver.py: Produces a lot of messages
[mit] Modernize
Improve code style
[aljazeera] Add unicode_literals marker
[nhl] Allow upper-case video IDs (Fixes #4494)
[screencastomatic] Add new extractor (Fixes #4497)
release 2014.12.17
[comedycentral] Match URLs with a second ID (fixes #4499)
release 2014.12.17.1
[downloader] Handle a file ./- (Fixes #4498)
release 2014.12.17.2
only add video-id to archive, when successful

Example:
no space left--> youtube-dl adds the id to archive, but the video isn't fully downloaded
Update YoutubeDL.py
Merge pull request #4501 from AndroKev/master

only add video-id to archive, when successful
YoutubeDL: style fix
[screencastomatic] Remove unused variable
[theplatform] Extract captions (Closes #4495)