add a count() method to Handler (+version bump)

Hi Jonathan,

Thanks for the code! I am using it add work and added a very simple addition.
I have a use case where I want to know how many times a call to a with a persistent response is made.
I find the count() method is easier than adding three calls to get and verifying that each one was done().

I am not tied to variable or function names so change away.

Thanks
Kyle