integration: Ensure that /srv/deployment/integration is present

The Jenkins slave servers use a collection of packages that are
provisioned with Trebuchet in production. In the integration labs
project however, we have not configured a Trebuchet deploy host and
instead use the contint::slave-scripts class to provision the same
content using git::clone{ensure => latest}. These clones need the
Trebuchet deploy root of /srv/deployment/integration to exist.

Change-Id: I7ab07aaa189799e1448c6d0ca42c5c219bcf8db4
Merge "integration: Ensure that /srv/deployment/integration is present" into production