Merge pull request #409 from waynegerard/label_field_name

Added a setter method for label_field_id in content_types.rb model

app/models/locomotive/content_type.rb

@@ -84,6 +84,13 @@ module Locomotive
       self.class.class_name_to_content_type(class_name, self.site)
     end
     
+    def label_field_id=(value)
+      # update the label_field_name if the label_field_id is changed
+      new_label_field_name = self.entries_custom_fields.where(:_id =>value).first.try(:name)
+      self.label_field_name = new_label_field_name
+      super(value)
+    end
+
     def label_field_name=(value)
       # mandatory if we allow the API to set the label field name without an id of the field
       @new_label_field_name = value unless value.blank?