Broken vint encoding, at least when interacting with OHCProvider

I haven't investigated this very closely so I only have a slightly hacky way to show the problem, but if you apply the patch attached, you'll see that the vints serialized and the one deserialized are not the same ones. If you remove the use of vints (as is currently on trunk, but only due to this issue because we do want to use vints), everything works correctly.

I'm honestly not sure where the problem is, but it sounds like it could be either in NIODataInputStream or in the OHCProvider since it's used on that test.