remove whitelist from demo

demo/vagrant/client1.hcl

@@ -12,9 +12,7 @@ client {
     # this should be like "nomad.service.consul:4647" and a system
     # like Consul used for service discovery.
     servers = ["127.0.0.1:4647"]
-    options {
-	"driver.whitelist" = " exec, qemu "
-    }
+    node_class = "foo"
 }
 
 # Modify our port to avoid a collision with server1