Add virtual env config on MacOS

zsh/.virtual_env_config.zsh_mac.example

@@ -0,0 +1,4 @@
+export WORKON_HOME=~/python-envs
+export VIRTUALENVWRAPPER_VIRTUALENV=/usr/local/bin/virtualenv
+mkdir -p $WORKON_HOME
+source /usr/local/bin/virtualenvwrapper.sh