[WIP] update mac configure script and add messaging about common port forwarding issue

update mac configure script and add messaging about port forwarding until we maybe use a better solution like how libtorrent does this, or RPC & UDP like this https://github.com/bmuller/rpcudp to avoid most port forwarding issues.
Per #619, we are strictly using Python 2.7 and we are considering moving to Python 3 once our dependencies are up-to-date. If you come across code that is assuming an earlier version of Python, please port it to 2.7.