Now that we are running zuulv3-dev.o.o, we are in a good place to
switch to the feature/zuulv3 branch for our ansible role.
Switch out zuul-server with zuul-scheduler.
Add python2-dnf to bindep.txt for fedora-25 job.
Change-Id: Ib61063c9b542e04f2f14a165f23bc82062714bf8
Depends-On: Id54a479e2e1b406cd5fd526ec6d2ee118b28b8d7
Signed-off-by: Paul Belanger <pabelanger@redhat.com>