[devtools] skip CubicWebServerTC on python3 People should migrate to wsgi if they're going to use CubicWeb on python3.

[web/test] switch unittest_web from twisted to wsgi And make it pass on python3 while at it.

[devtools] add CubicWebWsgiTC Similar to CubicWebServerTC, except using wsgiref instead of twisted as an http server.

[web/test] return the hash of uploaded files in FileUploadTC instead of their contents json must be unicode, which doesn't go well with arbitrary file contents. Compute the file hash instead, as we know the hexdigest is (ascii) text.

[web/test] open() as a context manager

[web/test] json.loads expects text, not bytes

[wsgi] fix handling of multiple posted files We were only keeping the last received file.

[web/test] Reword doc string for fileupload ajaxfunc

[skeleton] do not import the __pkginfo__.py module to make cubes installable via setuptools When using a simple "import" statement, running 'python setup.py install' for a cube fails in a fresh virtualenv due to the fact the install of the dependencies (here cubicweb iteself) is done by the python process doing the cube's installation, so the __pkginfo__ module from the cube is already loaded (thus used) when installing cubicweb... So we apply the third technique from: https://packaging.python.org/en/latest/single_source_version.html

merge changes from 3.22.2