Add Download Progress Bar

[blueworrybear]

Hi, I would like to add a download progress bar while installation.

It's because current version will display Your package has been installed! even if the package is still downloading.
It will look like the installation is success but the npm install not finished.

For example:

blueworrybear@LAPTOP-0K8IJ0NA:~/projects/covergates-node$ npm install .

> covergates@0.1.6 postinstall /home/blueworrybear/projects/covergates-node
> node ./install.js

Downloading release https://github.com/covergates/covergates/releases/download/v0.1.6/covergates-v0.1.6-linux-amd64.tar.gz
covergates has been installed!
^C
blueworrybear@LAPTOP-0K8IJ0NA:~/projects/covergates-node$ 

I have make a code change, which could be referred here: add download progress bar
With the update, the stdout will look like:

blueworrybear@LAPTOP-0K8IJ0NA:~/projects/covergates-node$ npm install .

> covergates@0.1.6 postinstall /home/blueworrybear/projects/covergates-node
> node ./install.js

Downloading release from https://github.com/covergates/covergates/releases/download/v0.1.6/covergates-v0.1.6-linux-amd64.tar.gz
covergates in now installing
  downloading [====================] 723152/bps 100% 0.0s


covergates has been installed!
npm WARN eslint-plugin-prettier@3.1.4 requires a peer of prettier@>=1.13.0 but none is installed. You must install peer dependencies yourself.

audited 138 packages in 45.738s

10 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

---

I love this project, it's very useful! So please consider this idea. I will make a PR if you agree.

[EverlastingBugstopper]

change looks good! will have to talk to @ispivey about PRs to this repo