Backporting the auto CSRF protection from 1.1 branch

The CSRF protection added in the PLIP 13679 (https://dev.plone.org/ticket/13679) could be also backported to Plone 4 (Plone need some fix, but it's working).

This fix will make plone.app.imaging working with recent plone.protect without side effects.

I think something like this should be better, according to our conventions:

´´´python
from pkg_resources import get_distribution

plone_protect_version = get_distribution('plone.protect').version
HAS_AUTO_CSRF = plone_protect_version >= '3.0.0'
´´´

see: http://ploneapi.readthedocs.org/en/1.0.0-rc.1/contribute/conventions.html#about-imports