In for a penny in for a pound. I also  noticed that #1786 resulted
in some funky looking console output. I've taken this opportunity to
tidy up our install script output whilst maintaining the information
useful for debugging install issues.

```
> node-sass@3.11.3 install /Users/xzyfer/Projects/Sass/upstream/node-sass
> node scripts/install.js

http node-sass install Downloading binary from https://github.com/sass/node-sass/releases/download/v3.11.3/darwin-x64-47_binding.node
http node-sass install Download complete
info node-sass install Binary saved at /Users/xzyfer/Projects/Sass/upstream/node-sass/vendor/darwin-x64-47/binding.node

> node-sass@3.11.3 postinstall /Users/xzyfer/Projects/Sass/upstream/node-sass
> node scripts/build.js

info node-sass build Binary found at /Users/xzyfer/Projects/Sass/upstream/node-sass/vendor/darwin-x64-47/binding.node
info node-sass build Testing binary
info node-sass build Binary is fine

> node-sass@3.11.3 prepublish /Users/xzyfer/Projects/Sass/upstream/node-sass
> not-in-install && node scripts/prepublish.js || in-install
```