RELICENSE: Byron Mallett

Added relicensing permission from Byron Mallett

RELICENSE/ByronMallett.md

+# Permission to Relicense under MPLv2 or any other OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by Byron Mallett
+that grants permission to relicense its copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2) or any other 
+Open Source Initiative approved license chosen by the current ZeroMQ 
+BDFL (Benevolent Dictator for Life).
+
+A portion of the commits made by the Github handle "mystfit", with
+commit author "Byron Mallett <byronated@gmail.com>", are copyright of Byron Mallett .
+This document hereby grants the libzmq project team to relicense libzmq, 
+including all past, present and future contributions of the author listed above.
+
+Byron Mallett 
+2018/9/1