Include binaries in npm package

[bindul]

When building in corporate environments, internet access is usually limited. While it may be possible to get access to npm registry through a controlled registry proxy, like nexus; it becomes harder when the package downloaded tries to go out to the internet to download further binaries. It would be great if the binaries could be included in the package, so install does not need intermet access beyond npm registry.

Perhaps related to #71 but different in that this issue requests not requiring a second download at all.

[Nettsentrisk]

That would also alleviate problems with relying on Github operational status. Right now almost all Github's services are experiencing degraded status, which causes this when trying to install this package:

optipng-bin@6.0.0 postinstall D:\a\1\s\src\WebSite\node_modules\optipng-bin
node lib/install.js

‼ Response code 502 (Gateway Error)
‼ optipng pre-build test failed
i compiling from source

If the binaries were in the package, this would never happen. Relying on Github always being operational is a vulnerability.