Realized ezmq connection events (connection accepted, connected, closed).
need_events option moved into the do_setopts method.
unit tests adaptated to the common tests.
Merge pull request #22 from RoadRunnr/master

enhance the test suite and travis run
Merge pull request #21 from anton-ryabkov/connect_disconnect_events_2

Realization of the EZMQ connection events
fully support IPv6 connections and run the ezmq test suite for v4 and v6
[RR-ony]: reduce travis test load and use travis badge for by repo