Revert "Add the possibility to work without python virtualenv"

This reverts commit f5eed8b7fb4d7d800a2f1a64ee985df34297f7b2.

Change-Id: Ibc1e0e2471ccde8beb3a2f50a19014425c5f71e9
Merge "Revert "Add the possibility to work without python virtualenv""