updating hom_ref and hom_var to work with alternate ploidies

fixes #228 

How do I wrap and parameterize  ```BOOST_AUTO_TEST_CASE( hom_ref_test )```?

I don't really understand how the macro expansions work, but it seems like if I pass a variable into it I get an error.  It looks like it's maybe creating a new type called hom_ref_test and then instantiating an instance of that?