Run yum repolist commands as root

Otherwise you get yum errors like [1] when you run stack.sh as !root.
The solution is to run yum commands as root so it can access the right
certs

[1] https://access.redhat.com/site/solutions/312413

Change-Id: I54b0df13508c50aba67e23da11953c536933917a
Don't use --skip-redirect for cinder restart on rhel6

RHEL6 doesn't support this flag so the restart fails.  Not exactly
sure why it is required, seems unchagned from the initial
commit 67787e6b4c6f31388cbee6d83b67371b31c443d4

(found running stack.sh with -e per [1])

[1] https://review.openstack.org/#/c/71996/

Change-Id: Ib34c3663409d7b96b932286cb5a6974e940075d3
Merge "Don't use --skip-redirect for cinder restart on rhel6"
Merge "Run yum repolist commands as root"