martinciu/nullobject — pull request #5 by mogox (2012-11-22 04:11:59+00:00)
Title: Adding support for to_s with params

Trying to fix this:

```ruby
#Before
FooNullObject.date.to_s(:us_date)
ArgumentError: wrong number of arguments (1 for 0)
...

#After
FooNullObject.date.to_s(:us_date)
""

```