change the name of the custom_keys exec to be "custom_keys" instead of using the alias metaparameter.

the reason for this change was because the Exec override was not able to find the exec through its alias

manifests/init.pp

@@ -167,8 +167,8 @@ class apt {
       recurse => true,
       mode => 0755, owner => root, group => root,
     }
-    exec { "find ${apt_base_dir}/keys.d -type f -exec apt-key add '{}' \\; && apt-get update":
-      alias => "custom_keys",
+    exec { "custom_keys":
+      command => "find ${apt_base_dir}/keys.d -type f -exec apt-key add '{}' \\; && apt-get update",
       subscribe => File["${apt_base_dir}/keys.d"],
       refreshonly => true,
     }