net_utils: added get_public_ip, using 'stun' package
qmd: when relaying, validate MAIL FROM against QMD

and refactored the code a little, to avoid redundancy
qmd: added config:check_outbound option
qmd: move the callback to the last argument

to get_qmd_response
Merge pull request #534 from msimerson/qmd

qmd: when relaying, validate MAIL FROM against QMD
Merge pull request #536 from msimerson/net_utils

net_utils: added get_public_ip, using 'stun' package
weirdly related enhancements

* move is_ipv4_literal from plugins/helo.checks to net_utils
	so it's available for the SPF plugin

* SPF: skip HELO tests for IP literals

* SPF: when a connection has relaying permissions, use our (Haraka's) public IP in the SPF mail_from query, to determine if Haraka has permisison to send on behalf of that MAIL FROM domain.

* move the public_ip setting out of config/connect.geoip.ini to config/smtp.ini, used by GeoIP and SPF plugins.

* updated connect.geoip to use boolean config options