Adding a method to create a new flavor with or without an extra_spec,
and a method to create a full server configuration, using a flavor_id.
This will allow the functional tests to build custom test servers.
Also splitting the setup_services method in _IntegratedTestBase in to
separate methods, for the functional tests to override it and
control the initialization of each service.
Change-Id: Ic5ef388f5daae7394d20bda5ed1db6f718564dbc
d799264c37