Add support for using a python virtual environment with load-all.sh.
Add support for using a python virtual environment with load-all.sh.

WadeBarnes/TheOrgBook,WadeBarnes/TheOrgBook,swcurran/TheOrgBook,WadeBarnes/TheOrgBook,swcurran/TheOrgBook,swcurran/TheOrgBook,WadeBarnes/TheOrgBook,swcurran/TheOrgBook,WadeBarnes/TheOrgBook,swcurran/TheOrgBook