Travis: Remove unused env variables
Travis: Remove unused env variables

ZMQ is set in build_libzmq.sh

interpretor/zeromq.js,lgeiger/zmq-prebuilt,lgeiger/zmq-prebuilt,lgeiger/zmq-prebuilt,interpretor/zeromq.js,interpretor/zeromq.js,lgeiger/zmq-prebuilt,lgeiger/zmq-prebuilt,interpretor/zeromq.js,interpretor/zeromq.js