use setuptools to dynamic load freeze pyzmq egg

use pkg_resources to load libzmq.{so,pyd}, which we could package pyzmq as a single egg file. it will make us we could deploy pyzmq on the fly.
use setuptools to dynamic load freeze pyzmq egg

refine code style as minrk's comments.
use setuptools to dynamic load freeze pyzmq egg

refine code style as minrk's comments.
use setuptools to dynamic load freeze pyzmq egg

refine code style as minrk's comments.
use setuptools to dynamic load freeze pyzmq egg

refine code style as minrk's comments.
Merge pull request #406 from phuslu/master

use import to load bundled libzmq in egg