Update docker tutorial

 * Use the standard installation instruction instead of the master
   version: 0.7 has been out for some time now.
 * As a result, switch to `sudo docker` instead of `sudo ./docker`.
 * Publish ports when running buildbot to be able to log into ssh and
   see the buildbot frontend.
 * Reformat the text
Sorry, I created a confusion: yes, it's publish all _exposed_ ports, not all ports.  So according to the `Dockerfile` we have, it's gonna be 8010 and 22 only.

However, I just tried the instructions and `--publish-all` did not really give me the expected result: `telnet localhost 8010` -- connection refused.