Add DEPLOYMENT_MODE to local_settings.py

DEPLOYMENT_MODE determine if we do flavor matching, it can be "poc" (No) or "scale" (Yes).
This is used in Tuskar-ui to show flavor administration options etc.

Change-Id: I6a1b1cbb9cfe8d2750023d6ea633cf3390468c43
Merge "Add DEPLOYMENT_MODE to local_settings.py"