Revert to using /tmp fir for cwd for virte inst.

If the virtualenv target directory does not exist before running the virtualenv
command the puppet command will fail if the cwd does not exist, hence revert
back to using the /tmp directory for current working directory.
Silence facter by redirecting python -V stderr
Fix Python version detection, stderr to stdout
Merge pull request #51 from jalli/master

Fix secondary version detection for python and revert back to using /tmp for current working dir during virtualenv install.