Fix Python 3.3 calling another virtualenv as a subprocess.
Add os import
Merge pull request #48 from mdboom/osx/framework-fix

Fix Python 3.3 calling another virtualenv as a subprocess.
Add version check for incompatible Python 3.x/virtualenv 1.11 combination
Merge pull request #47 from mdboom/virtualenv-check

Known issue: Running in Python 3.3 asv master with virtualenv 1.11
Fix Travis