Refresh the First-run instructions.

- Move to pip
- Don't activate the virtualenv (IMO not necessary)
- Put less emphasis on docker.
- Remove the use of tail
- Refresh the logs (2011 and 2009 !)
- Explain a bit more what the commands are for.
Update after review from Dustin.

- One sentence per line
- Restored the ``code-block``s
- language fix
Merge branch 'patch-3' of github.com:benallard/buildbot into patch-2