[WIP] testing varnish config

This PR defines the ressources that should be "protected" by varnish.

To test varnish configuration for production:

     ./buildout/bin/nosetests --tc-file=buildout_prod.cfg chsdi/tests/varnish/

for `dev`and `int` use `buildout_dev.cfg`and `buildout_int.cfg`respectively.
Where is this used?