[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
\.svn
^build$
^dist$
\.egg-info$
^.tox$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/cubes/.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/