Fix remove column call to work in Rails 3 and 4

Removes `column_type` and `column_options` so that it works well in both
versions.

Backcported from master, to release a patch version with this bugfix.

[closes thoughtbot#1947]

lib/paperclip/schema.rb

@@ -40,7 +40,7 @@ def remove_attachment(table_name, *attachment_names)
         attachment_names.each do |attachment_name|
           COLUMNS.each_pair do |column_name, column_type|
             column_options = options.merge(options[column_name.to_sym] || {})
-            remove_column(table_name, "#{attachment_name}_#{column_name}", column_type, column_options)
+            remove_column(table_name, "#{attachment_name}_#{column_name}")
           end
         end
       end