Call rpm --whatprovides on packages required to run puppet

We install the packages with one yum command but it won't return
error if some of the packages are missing. We better check that
using rpm.

Change-Id: Ie2537c5c0e3348d2c7df6b9bfc40939985171b45

packstack/plugins/puppet_950.py

@@ -154,6 +154,9 @@ def install_deps(config, messages):
                           % packages)
         server.append("yum update -y %s"
                           % packages)
+        # yum does not fail if one of the packages is missing
+        for package in deps:
+            server.append("rpm -q --whatprovides %s" % (package))
         server.execute()