Find unzip command line for Mac

[DavidBruant]

In #103, we merged a change that is known to not work on OSX.
We need to find the equivalent of

city-core/tools/unzipCUB3ds.js

Line 108 in ead6187

var unzipProc = spawn('unzip', args);

that runs on mac

[DavidBruant]

Well... or just create a docker image in which we can run the script?