Switched from decompress-zip to extract-zip

[nsainaney]

Fixes #254

[philnash]

I came here to merge this PR, but I can't get the tests to pass. It looks like something has changed with ngrok's behaviour around auth tokens. I've reached out to the ngrok team to see if this is expected and how it should work from now on. Until I hear from them, I will hold off on merging.

Cheers, Phil

[philnash]

Hey @nsainaney, I've finally got around to sorting this out. I fixed the issue with the tests (it was a change in ngrok's behaviour) and I've pushed that fix to the master branch.

The only issue with this PR now is that you overwrote the ngrok stub in the repo. Would you be able to rollback to the original stub, then run git update-index --assume-unchanged bin/ngrok so that you don't override it in git when running npm install. (These instructions are under "Contributors" in the readme, I might start work on a CONTRIBUTING.md file to make this more obvious).

While you are updating that, if you can merge the latest from master, then getting this PR merged will be even easier for me.

Thanks!