tests to detect existing bugs

Hi,

I think I found two bugs in romkan:
 - to_hepburn しゅ → sfu
 - to_kunrei っしゅ → sshou (rather than ssyou)

I don't know how to fix them (seems to be something about how KANROM is built?), but in case you're interested, I added unit tests to catch these two.  I also had to make some changes to test.py so that it would run in my machine.  If you think they're useful, feel free to pull!