Xcode 10 support on macOS

[dcaravana]

No description provided.

[coveralls]

Coverage remained the same at 95.455% when pulling 7ca125c on CrowdEmotion:master into 231a3b5 on XadillaX:master.

[XadillaX]

Well done!

Would you please add a test environment about your changes in .travis.yml? Thx

[XadillaX]

BTW, I can install this package under macOS. What is this PR mainly for?

$ npm install mp4duration

✔ Installed 1 packages
  CXX(target) Release/obj.target/mp4duration/src/mp4duration.o
  CXX(target) Release/obj.target/mp4duration/src/parse.o
  SOLINK_MODULE(target) Release/mp4duration.node
✔ Run 1 scripts
✔ All packages installed (2 packages installed from npm registry, used 5s(network 1s), speed 370.93kB/s, json 2(4.89kB), tarball 378.29kB)

[dcaravana]

This is a fix for Xcode 10, see nodejs/node-gyp#469.

Is Xcode 10 installed on your Mac? That would explain why you managed to install the module.

I'll add the environment next.

[dcaravana]

Finally managed to configure Travis... Apologies for the many tries but I got confused by the many sources of discording fixes and the non-linear support for env matrix.
Still not perfect but it's testing what we need to test.

[XadillaX]

1.0.0 released.