Prepare this module for Contrail 1.20

This commit introduces a number of changes required to make the module
work properly with Contrail 1.20. The changes are:

* the renaming of the configuration files for the Control and Discovery
  services (depending on whether contrail 1.06 or 1.20 is in use)

* modifications required to ensure that vhost0 is set up properly (the
  commands required to do that changed from 1.06 to 1.20)