added dependency on pyzmq and limited to version 2.* to prevent incompatibility on pyzmq 13.*

        modified:   setup.py
resolved use of int_sockopts which were moved from zmq.core.constants to zmq.sugar

setup.py got removed unused import

        modified:   lib/zmqc.py
        modified:   setup.py
Merge pull request #7 from vlcinsky/opts_moved_to_sugar

Resolved problem with import of int_sockopts which were moved from core to sugar