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.
One sentence per line, please

"Thank*s* to.."

It might be better to move the Docker warning to the Docker page -- it sounds a little scary here in the second paragraph of the Buildbot tutorial.