Upgrade setuptools to 1.10 or more in a newly created virtualenv

By default, virtualenv embeds setuptools, and doesn't download its
latest version. At the moment, latest virtualenv is 1.10.1, which does
install setuptools-0.9.8

Unfortunately, setuptools-0.9.8 doesn't manage correctly HTTPS
certificates if the user is specifying a proxy with https_proxy and
http_proxy environments variables. This can raise an error if the
server to download is having TLS2_3 HTTPS certificate, by example when
pip installing python-novaclient, whick asks for
https://pypi.python.org/simple/pbr

Fixes: bug #1201253
Change-Id: I7cca000857f7691d4cb723d0a0c22a202da703f8