Install polkit on Fedora/openSUSE when using nova

We clearly depend on polkit. It's usually already installed, but for
people using JeOS images, it's not.

Change-Id: Ieccd0ff569f7d4541833b98232aeebb36b3493cb
diff --git a/files/rpms/nova b/files/rpms/nova
index 7ff926b..9d8891d 100644
--- a/files/rpms/nova
+++ b/files/rpms/nova
@@ -15,6 +15,7 @@
 m2crypto
 mysql-server # NOPRIME
 parted
+polkit
 python-boto
 python-carrot
 python-cheetah