Avoid duplicate package errors by virtualising them

If you set up both the server and client on the same RedHat machine,
you get a duplicate package error as they both depend on 'openldap'.
Making the package definitions for these virtual and then realizing
them immediately afterwards, we avoid that issue.
Merge pull request #14 from PeterJCLaw/fix-duplicate-package

Fix #12: Avoid duplicate package errors by virtualising them