Use correct WSGI dir on SUSE distros

The current default (/var/www) leads to:

AH01797: client denied by server configuration:
/var/www/keystone/admin

For /var/www the needed permissions on SUSE are not set.
For /srv/www/htdocs/ the permissions are correct on SUSE systems.

Change-Id: I3f2df896daecdfe510d45ff121af2a8433a4d5be
XenAPI: stackrc now depends on nproc

Install it automatically in the devstack DomU

Change-Id: Ie282dd128ebc92377d85800585962bc8767483fe
Merge "Use correct WSGI dir on SUSE distros"
Merge "XenAPI: stackrc now depends on nproc"
Merge branch 'master' of https://github.com/openstack-dev/devstack