Attempted fix of "cannot create virtualenv for python 3.4" bug by upgrading virtualenv

https://issues.jenkins-ci.org/browse/JENKINS-22902

Not sure whether this will work or not, but thought I'd throw it out there in case it helps.  Just naively upgrades virtualenv.py, and adds in its new dependency, which is a virtualenv_support folder.

I've been trying to run the tests using `mvn install`, but I get 20 failures, not matter whether I run my patched version, or the old version from master, or the 0.2.0 release tag...