[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.
If `pip` should be installed, then this should be done via https. See the [guide](https://python-packaging-user-guide.readthedocs.org/en/latest/installing.html#setup-for-installing-packages) on how to do so. Though, if `brew install python` really installs `pip` as well, we needn't bother any further.