plone.recipe.varnish does not support varnish 3 and zope2_vhm_map

zope2_vhm_map does not properly work with varnish_version 3 due to needing to use the varnish 3 string concatenation operator.

https://www.varnish-cache.org/docs/3.0/installation/upgrade.html#string-concatenation-operator

remote: Message from VCC-compiler:
remote: Expected ';' got 'req.url'
remote: (program line 174), at
remote: ('input' Line 22 Pos 114)
remote: set req.url = "/VirtualHostBase/http/example.net:8080/Plone/VirtualHostRoot" req.url;
remote: -----------------------------------------------------------------------------------------------------------------#######-
remote:
remote: Running VCC-compiler failed, exit 1
remote:
remote: VCL compilation failed