Restrict permissions on cinder configuration

Prior to this commit, the puppetlabs-cinder module applied the mode
0644 to the File[$::cinder::params::cinder_conf] resource which
were too permissive. This commit explicitly sets the mode to 0600.

manifests/base.pp

@@ -32,7 +32,10 @@ class cinder::base (
     require => Package[$::cinder::params::package_name],
   }
 
-  file { $::cinder::params::cinder_conf: }
+  file { $::cinder::params::cinder_conf:
+    mode => '0600',
+  }
+
   file { $::cinder::params::cinder_paste_api_ini: }
 
   # Temporary fixes