seqmon: configurable parsing & socket identity

This change makes the ZMQ socket identity and input parsing behavior
configurable using command-line switches.

Change-Id: Iff271246469e03a0cd6e8c715365aaa2499c8dd5
zmq2log fix-ups to unicode and zmq handling

Do not default to a socket identity equal to the current hostname;
instead, set no socket identity at all unless explicitly specified.

Change-Id: Iea8255ed675850cb7f3071b08215d98472499491