update Session to IPython 0.14 wire protocol
stop barfing to STDERR
fix displayhook
switch to ffi-rzmq (for libzmq3 support)

and fix recv / heartbeat logic

busy wait, double-serialiazation, heartbeat blocked GIL (or whatever the equivalent was)
ffi-rzmq error checking
don't trigger display hook on empty arrays

I know it's weird, but things like puts return empty arrays
Merge pull request #1 from minrk/master

ffi-rzmq and some fixes by minrk