Detect missing packages with yum

yum -y doesn't report an error when packages are missing (see [1] for
upstream discussion).  Thus we run the output of yum through a small
awk script looking for missing packages output.

The one change required for RHEL is that python-wsgiref is included in
the distro python, so doesn't need a separate package.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=965567

Change-Id: I9908ff4edbf2b0d961d25837a08a34e1417bbb02
diff --git a/files/rpms/glance b/files/rpms/glance
index 25c5d39..534097a 100644
--- a/files/rpms/glance
+++ b/files/rpms/glance
@@ -13,6 +13,6 @@
 python-paste-deploy #dist:f18,f19,f20,rhel7
 python-routes
 python-sqlalchemy
-python-wsgiref
+python-wsgiref      #dist:f18,f19,f20
 pyxattr
 zlib-devel          # testonly