Allow to not manage Tempest code in Puppet

In the case you are using a package, you may want the flexibility to not
use VCS to manage Tempest code and just use the Puppet module to
configure Tempest itself.

Adding a new parameter, true by default to keep backward compatibility.

Change-Id: I6d5c17393630fda156bebc55fe28f97bcabecca4
Merge "Allow to not manage Tempest code in Puppet"