In order to do a developer mode that allows installation of packages
from local file, which take precedence over the developer_mode
constraints, we need to allow the order of the constraints to be
changed.
This patch adds a "pip_install_developer_constraints" var which is used
to set the developer mode constraints. By default this will leave the
same behaviour but will allow additional constraints to be added, or the
developermode constraints file to be overriden altogether.
Change-Id: I010fcbd9b4c66b29fc0961818038bb75ba815c9a
935fde61e0