Revert __refresh() because it doesn't do anything.

This reverts commit 5561d9538cccb4478bffdf2f4cd51cf2bb5f8e93.
Don't follow internal pointer if the object is of incorrect type
Add method to forcibly destroy the libusb object (for debugging and bug workarounds)
Fix `npm run-script valgrind`

Valgrind messes up node somehow such that the coffeescript compiler fails
in it.
0.3.11