Check the checksum after download

[satoshun00]

ref: #32 (comment)

actual: require('crypto').createHash('sha256').update(file).digest('hex')
expected: https://github.com/gohugoio/hugo/releases/download/v0.31/hugo_0.31_checksums.txt

[XhmikosR]

Hmm, this should be easy to add, but I can't find any way to make bin-wrapper not delete the dist file so that we can check the checksum.

[satoshun00]

I'll do it this month.

[satoshun00]

I found that is not easy to add checksum validation as long as hugo-bin depends on bin-wrapper that have no 'downloaded' (before decompress) event interface.
For this, I think I should remove bin-wrapper I see that is not well-maintained from dependencies.

Or I'll see if it's possible to expose before decompress event from bin-wrapper.

[XhmikosR]

@satoshun00: this might give you some ideas https://github.com/nikku/hugo-cli

[XhmikosR]

I rebased and updated https://github.com/fenneclab/hugo-bin/compare/feat/checksum and it works. My thoughts:

1. I do believe that the checksum functionality should be in bin-wrapper. If someone provides a proper PR against my fork, we could move forward
2. The checksums should be retrieved from GitHub so that we don't need to handle this ourselves here

Any help is welcome 🙂