Suppress non-error output of `systemctl enable`

The `systemctl enable` command ordinarily prints the `ln` command used
to enable the unit to stderr, but that's not ideal in the vagrant setup
because it gets printed in red, which should be reserved for errors, but
it's not a real error.

Set an environment variable to raise the log level to prevent `info`
messages from being printed to stderr (as they are not actually errors.)

I looked into the `systemctl` calls happening from the Salt setup script
to understand why they were not going to stderr, and it turns out the
Salt script will redirect all messages to stdout so they will all be
green regardless...

Tested:
- Started a fresh Vagrant cluster, confirmed no red messages in output
  when creating the cluster successfully. Successfully started nginx
  through Kubernetes using cluster/kubecfg.sh.
- Confirmed that the salt-api service was up after `vagrant up`:
  $ vagrant ssh master -c 'systemctl status salt-api.service'
  salt-api.service - The Salt API
     Loaded: loaded (/usr/lib/systemd/system/salt-api.service; enabled)
     Active: active (running) since Fri 2014-08-29 23:19:47 UTC; 11min ago
   Main PID: 2090 (salt-api)
     CGroup: /system.slice/salt-api.service
             +-2090 /usr/bin/python /usr/bin/salt-api
             +-2110 /usr/bin/python /usr/bin/salt-api

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Merge pull request #1112 from filbranden/vagrant_salt_master2

Redirect output of `systemctl enable` to stdout
Simplify labels for `kubecfg run`

We created a name=<controller name> label on each object we created.  This was confusing.  Instead, piggyback on `replicationController` label and use that as the selector.
Add template update to rollingUpdate
Pretty up the demo a little.

Use images and some better formatting.  Also add scripts to help prevent typos.
Fix/expand kubecfg unit tests
Add containerPort to services in guestbook example
Use KUBECFG instead of CLOUDCFG in scripts
Fix up e2e test for update demo.

Use the scripts that are in the example directory.  Also actually run the update as part of the test.