[rackspace|storage] Add copy method to Rackspace::File.

lib/fog/rackspace/models/storage/file.rb

@@ -29,6 +29,13 @@ module Fog
           @directory
         end
 
+        def copy(target_directory_key, target_file_key, options={})
+          requires :directory, :key
+          connection.copy_object(directory.key, key, target_directory_key, target_file_key)
+          target_directory = connection.directories.new(:key => target_directory_key)
+          target_directory.files.get(target_file_key)
+        end
+
         def destroy
           requires :directory, :key
           connection.delete_object(directory.key, key)