Make it possible for someone to config
PIP_UPGRADE=True
in local.conf and thus force pip_install calls to upgrade. In
automated testing this is probably a bad idea, but in manual testing
or situations where devstack is being used to spin up proof of
concepts having the option to use the latest and greatest Python
modules is a useful way of exploring the health of the ecosystem.
To help with visibility of the setting, and section has been added
in configuration.rst near other similar settings.
Change-Id: I484c954f1e1f05ed02c0b08e8e4a9c18558c05ef
ebdd9ac5b4