Make ironfan work with string (in addition to array) for cluster_path…

…, to conform to chef semantics (fixes #130)

lib/ironfan.rb

@@ -29,7 +29,7 @@ module Ironfan
 
   # path to search for cluster definition files
   def self.cluster_path
-    return Chef::Config[:cluster_path] if Chef::Config[:cluster_path]
+    return Array(Chef::Config[:cluster_path]) if Chef::Config[:cluster_path]
     raise "Holy smokes, you have no cookbook_path or cluster_path set up. Follow chef's directions for creating a knife.rb." if Chef::Config[:cookbook_path].blank?
     cl_path = Chef::Config[:cookbook_path].map{|dir| File.expand_path('../clusters', dir) }.uniq
     ui.warn "No cluster path set. Taking a wild guess that #{cl_path.inspect} is \nreasonable based on your cookbook_path -- but please set cluster_path in your knife.rb"