Tailing without tears or fears

Hey friends! How often do you `ssh ubuntu@... 'tail -qf /var/log/init*'` after you `stemcell`? If you're like me, doubtlessly quite often. Chalk it up to the desire to know more, or a growing impatience with the things of this world — but perhaps you're worried that these few extra keystrokes may shorten your life... or worse?

Well... within this pull request, I have hidden the secret to a better way. Now, you can simply launch your instances with `stemcell` and get your tail for free. Just append `--tail` to the end of your `stemcell` command and `net-ssh` will lovingly shepherd the bits back to your terminal.

`$ stemcell monorail-web --tail`

```
I, [2013-10-15T18:48:28.513823 #8685]  INFO -- : launched instances successfully

Tailing the initial converge. Press Ctrl-C to exit...

You're launching more than one instance.
Showing you on the output from i-f5d0408d.

Waiting for sshd.... UP!
Server responded with: SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1

... /var/log/init exists!
starting chef bootstrapping...
updating apt repo
+ echo updating apt repo
+ apt-get update
```

/cc @igor47 @martinrhoads @pcarrier @daveaugustine @jeffyip @patrickviet @jtai