Problem: inconsistency between installed czmq and git snapshot
Problem: inconsistency between installed czmq and git snapshot

Solution: load API models in /usr/local and /usr. Order of preference is

    1. current dir for git snapshots
    2. /usr/local/share/ for results of make install
    3. /usr/share for installed rpm or Debian packages

This is the way we can control the API version of czmq et all and use
and develop czmq from git at the same time on the same machine.

zeromq/zproject,zeromq/zproject,zeromq/zproject