only do initthreads for CPython
fix Context destruction / Socket gc
avoid imports from zmq.core
Frame is just a dummy, it doesn't actually have a zmq_msg_t handle
add skip decorators (required for 2.6)
fix Context gc test on PyPy
use zmq.proxy in zmq.device
ensure sockets are cleaned up in a few device tests

PyPy is bad at garbage collection
skip stopwatch tests (until stopwatch is defined in cffi)
skip some tracker / refcounting tasks on PyPy
bundled libzmq doesn't work on PyPy
add pure Python monitored queue (for PyPy)
add __pycache__ to gitignore
Merge pull request #2 from minrk/pypy

Some PyPy fixes