Separate twisted-specific configuration from WebConfigurationBase class This is in preparation of dropping the Twisted web server backend. We thus draw a clearer line between what's specific to twisted from what's generic by moving WebConfigurationBase class into cubicweb/web/webconfig.py and only keeping twisted-related in AllInOneConfiguration (still living in cubicweb/etwist/twconfig.py).

[bdist_wheel]
universal = 1

[check-manifest]
ignore =
  debian
  debian/*
  cubicweb.spec
  __pkginfo__.py