Saharaclient must be installed for UI to work in dev environment

Since in dev install guide we create a symlink to saharadashboard instead
of installing it, its dependencies are not installed automatically. So we
need to manually install saharaclient. Thanks to Yaroslav for finding
that issue.

Change-Id: I319ff3aaf6df86e473d4b0206f9769938074c6f8
(cherry picked from commit 01cc56d25d04a2f5a7b0c1ff32cf11b16c06edd0)
Fix up DevStack guide

For some reason DevStack instructions were on page
"Setup VM for DevStack on OSX" which is rather weird. I've shuffled the
instructions and section names to make them more consistent.

Change-Id: Ib48808b202c9a640f1e673611bd9f521b03368c7
(cherry picked from commit f39726cc4ddff12faf0db87bd96d6cb22220c8c4)