Fix expire_all_in_set-method and back it with a test.

Hello,

I was trying to use the expire_all_in_set-method, but got the following TypeError (both in Python 2.7.6 and 3.2.5):

    TypeError: filter expected 2 arguments, got 1

I took a look at the code and propose the following changes to fix this method. I did also include a test to verify the correct functionality.

Best regards ~