Bug#707893: a newer version packaged

[Gediminas Paulauskas]

There is a newer version of zc.buildout 1.7.1 with packaging updates from
Ubuntu committed to http://anonscm.debian.org/viewvc/pkg-zope/zc.buildout/ .
There is also a tag, but it has not been uploaded in fact. Uploading it
will remove the binary dependency on python2.6