Extract .tar.gz files using native tar or 7z.exe when possible

[benjamn]

For the sake of portability, the files.extractTarGz method is currently implemented in terms of a pure-JavaScript library: https://www.npmjs.com/package/tar

Portability is nice, but speed is also nice. On my machine, it takes 25 seconds to extract the fourseven:scss package using the npm tar package, whereas it takes only 3.5 seconds to extract it using the native tar command. On Windows, the time drops from 36 seconds to 8 seconds.

The time savings for even larger packages like meteor-tool are even more dramatic: 45 seconds vs. 4 seconds on my Mac.

This pull request uses the native commands when possible, but falls back to the npm tar library if the native commands don't work for any reason.

For Windows, we now include a standalone 7z.exe binary in the dev bundle (i.e., dev_bundle\bin\7z.exe), though tar will also work on Windows if it's in the $env:PATH. This is the standard 7-Zip 16.02 program available here. I believe this usage is compatible with the 7-zip license, according to the FAQ.

I think these changes may be too risky to ship with Meteor 1.4, given that it's now in the release candidate stage, but if all goes well we will ship them soon after that release (likely 1.4.1).

cc @tmeasday @zol @abernix

[benjamn]

The options.forceConvert boolean is no longer passed by any callers.

[s-devaney]

Could the status of the extraction be added to the update process? At the moment it says "downloading" rather than "extracting" etc

[abernix]

@s-devaney This is a good idea. I've looked at this recently, but currently they're in the same sub-task so the message doesn't change. I think assuming that this PR works okay, it will be possible to improve the messaging. For now, as Ben mentioned above, meteor run --verbose will be super informative.

[benjamn]

@s-devaney I'll add a commit that reflects that, thanks!

[benjamn]

The build messages now distinguish between downloading, extracting, and loading packages. Thanks to this PR, the extraction is now by far the cheapest part.

[benjamn]

@tmeasday should I hold off on merging this until after 1.4.0.1?

[tmeasday]

Yeah, although I can create a release branch for 1.4.0.1, so merge it whenever