Remove unused dummy zLOG implementation.

This module contained a dummy implementation of zLOG originally used in
cgi/TAL/XMLParser.py. Since reference to zLOG in XMLParser.py is already
commented out, zLOG.py is no longer needed. The dummy implementation can
never have worked as it doesn't contain the INFO and PROBLEM definitions.
Thanks to Cheer Xiao for spotting this.

Author: schlatterbeck