remove psutil dependency under windows
reverts documentation commit 96aba067a8 because
it prevent sphinx build
merge setup source code and vcs checkout sections and simplify wording
simplify source installation instructions for windows
* The dashboard from the backend howto doesn't specify "name" field
which causes non-null constraint violation.
* Some useful examples uses idea.idea" model which isn't available in
8.0 so I replaced them with "note.note".
closes#3993
Antony Lesuisse
Nicolas Lempereur
Raphael Collet