Mem fixes

Hi Joel,

Finally got around to looking at this.  Basically the problem(s) were related to memory access/management errors.  This pull request should have the fixes necessary to at least get the timer stuff working.  I've also included the valgrind wrapper script I used to help identify a lot of the problems.

I still think starting with a pure UV::FFI bindings module and then building the Reactor interface wrapper on top of that is the way to go.  However I at least wanted to give you some idea of what was going on with your current implementation.

I think you're right about not really needing the pack/unpack fu (and I didn't need any for these fixes), since we're mostly just passing callbacks to libuv and not doing much data manipulation.

I'm traveling this week but if you still want to bang this stuff out maybe we can get together next week for a mini-hackathon.

Cheers!