Allow for conditional ENV override of admzip

It is sometimes preferred to use an external program for unzipping instead of
AdmZip. In chromedrivers case it seems to be causing some bugs/issues on
certain platforms. Allow for a native circumvention.
Shouldn't this be a call to `deffered.reject` instead of a log to the console?
The params `-d` and `-o` are also fixed, I believe they too should be an environment variable, otherwise we are just limiting the options. Maybe try `exec` instead of `execFile`, which does not take an array as arguments.