Handle MacOS 10.11.5+ interface changes and VM use case

[eriktrom]

• allow portfinder.getPort for all ports w/ os.networkInterfaces().internal === true
• allow portfinder.getPort from netmask 255.255.255.0, which maps to
  ip address given to default interface of machine (en0)
• allow portfinder.getPort to work from within a locally running VM assuming
  vnic0 or vnic1 use netmask 255.255.255.0 (aka, shared or bridged mode)
• handle 0.0.0.0 host that while not output by os.networkInterfaces() is
  nonetheless a bindable host that exists and must be handled accordingly

cc @indexzero or @stefanpenner - need at least one pair of eyeballs on this one. Thanks!

[eriktrom]

cc @dbuhrman - does this fix your use case? (if you have time to check thanks, if not, no biggie)

[stefanpenner]

@eriktrom it seems good, but without tests its hard to see exactly what use-case this is addressing so Im not sure my feedback is that valuable as I haven't played with 10.11.x yet myself.

[eriktrom]

@stefanpenner - thanks for the review - the tests did get an update - they iterate over the exports._defaultHosts now, so they reflect the current changes.

Gonna merge - if we find issues, I'll make another PR

Thanks again for the review

[eriktrom]

@indexzero - can you make a release to npm? Gratzi!

[Turbo87]

@indexzero it would also be awesome if you could add @eriktrom as a collaborator on NPM to reduce the bus factor of this project

[indexzero]

@eriktrom @Turbo87 done. Feel free to publish at will. Good job here 👍

$ npm owner ls portfinder
npm info it worked if it ends with ok
npm info using npm@3.10.5
npm info using node@v4.4.3
npm info attempt registry request try #1 at 1:17:33 PM
npm http request GET https://registry.npmjs.org/portfinder
npm http 200 https://registry.npmjs.org/portfinder
eriktrom <erik.trom.github@gmail.com>
indexzero <charlie.robbins@gmail.com>
npm info ok 

[eriktrom]

Thanks @indexzero 👍