Minor improvements

Hi, 

I've played a little with your library on one project where I needed to have test-driven tests. I liked your library and used for the project. I thought two minor improvements could be made:

(1) when custom data type converter is used, make the converter aware of the param name. With current version, i was not able to use (without workaround) the same type & converter multiple times for one test method -- I was not able to process data differently
(2) add support for default / global test record entries. I my test, I wanted to always have first parameter the same (the path to directory from where I was reading my test data files). I had to copy the param & value to every test record, which worked, but when I needed to change the path, I had to change it in each test record.

I've implemented both (I believe :-) if you could incorporate & enhance it into your core lib and have in some future version, that'd be awesome.

Thanks, have a great day,
Josef