Note from IG: James (and/or his collaborator?) have modified the .cu files
here from Alex's original code, it's not just a wrapper. James doesn't remember
what they changed, and his commit messages just say things like "mega-commit".

I've made some bug fixes here and haven't bothered to push them back to
TheanoLinear, so when handling updates from TheanoLinear, merge them carefully.
This includes:
1) Removed "border_mode" argument which had no effect
2) Fixed some unit tests that weren't passing enough arguments
