Forked from #1649.

This PR adds a small ascii progress bar to the binary download.
Stalled installations make up a steady background noise of our
issues. It's my hope that by making the binary fetch more
transparent we can stem the tide of those issues.

In order to address @saper's [concerns][1] this progress bar will
respect npm's `progress` config flag.

Downloading
```
Start downloading binary at https://github.com/sass/node-sass/releases/download/v3.8.0/darwin-x64-48_binding.node
Total 2602136 [===============          ] 1566256 60% 4.9s
```
Success
```
Start downloading binary at https://github.com/sass/node-sass/releases/download/v3.8.0/darwin-x64-48_binding.node
Total 2602136 [=========================] 2602136 100% 0.0s
Binary downloaded and installed at /tmp/node-sass/vendor/darwin-x64-48/binding.node
```

[1]: https://github.com/sass/node-sass/pull/1649#issuecomment-242720257