Brought check_output into geturl and deleted check_output to ease deployment

I think that check_output.py should be added into the geturl file as it's small and the benefits of splitting up and simplifying the code are outweighed by the inconvenience of setting up the module in the python path. A single file makes deployment a lot faster.

(See https://github.com/uams/geturl/issues/9 for people having trouble with check_output.py - this would fix this).