Fix gevent dependency requirement in documentation and REQUIREMENTS.txt

gevent-1.0 has been released and it's available both on PyPI and on
Ubuntu 14.04: there's no need for instructions to install the git
development version.
Display testcases codenames in submission results for admin.
Consistently use __future__ imports in all files

Just absolute_import, print_function and unicode_literals for now, and
exclude unicode_literals from cmscontrib, cmstaskenv and cmstestsuite.
Use proper project name in copyright notices
Fix empty __init__.py files

Remove any copyright claim and add __future__ headers.
Use io.open instead of open or codecs.open
Allow uploading testcases archive in AWS
Wrapped the zipfile upload to catch bad zip files.
White spaces must be a bytes string.

Also, extend the set of white spaces with those defined by Unicode.
Typo in docs.
Fix pep8 warnings.
Simplify interface for java tasks.

Also add a fake updater to issue warning on the changed semantic of
the Java compilation.
Amend documentation for new languages.
Add tests for managed tasks in Java.
Add communication and managed functional tests for Pascal.
Don't allow contest.start and contest.stop to be null
Allow admins to limit the localizations of CWS available to users

Co-authored by Luca Wehrstedt.
Add interface for users to choose CWS localization, overriding browser

Co-authored by Luca Wehrstedt.
PEP8
Fix ambiguity in documentation (database setup)