`swarm-stack-intro` refers to removed `visualizer` application from `example-voting-app`

[Privat33r-dev]

visualizer was removed from example-voting-app in PR#273, but it is still referred to in the swarm-stack-intro multiple times:

play-with-docker.github.io/_posts/2017-01-28-swarm-stack-intro.markdown

Line 94 in 032f83d

10rt1wczotze voting_stack_visualizer replicated 1/1 dockersample

play-with-docker.github.io/_posts/2017-01-28-swarm-stack-intro.markdown

Line 126 in 032f83d

Finally, we can check that our [APP](/){:data-term=".term1"}{:data-port="5000"} is running, the [RESULT](/){:data-term=".term1"}{:data-port="5001"} page is also available as well as [SWARM VISUALIZER](/){:data-term=".term1"}{:data-port="8080"}

As well as number of services in the example is invalid (real amount is 5):

play-with-docker.github.io/_posts/2017-01-28-swarm-stack-intro.markdown

Line 81 in 032f83d

voting_stack 6

I see 2 potential solutions:

1. Use fork/frozen older version of the example app.
2. Update the tutorial's text, removing references to visualizer.