In order to allow tests to work as the use of the common
role is implemented in the various roles, we pre-implement
the addition of the role into the a-r-r file.
Change-Id: I96a4bff650aa50ba7e388bb34084524543c08a8f
Implements: blueprint python-build-install-simplification
Signed-off-by: Jesse Pretorius <jesse.pretorius@rackspace.co.uk>