Inform RPi users that npm install take a long time

When I installed MM on my Rpi3 last night, I was quite surprised to see how long it took, without any info at all given to the user while waiting. We live in times of impatience, so when the npm native progress indicator disappeared for almost 8 minutes, after 2 minutes of completing many progress bars, I was getting concerned. Especially given that installing the entire OS only took about half the time.

cd $HOME
git clone https://github.com/MichMich/MagicMirror.git
cd MagicMirror

# Install node dependencies (on Vanilla Stretch)
npm install
...
<eat your nails>
<scratch your balls (or what have you)>
<rip your hair out>
...
added 811 packages in 568.737s

That is almost 8 minutes without any progress bar! Also, a basic MM install, take up: 348 MB (not including any additional OS related installations.)

cd $HOME/MagicMirror/ && du -sh ./

We should put this in the README. I’m sure many (and even technical) users may freak out long before those 10 minutes are up.

[amcolash]

Ironic that I was just browsing the issue tracker, I just updated my rpi2 mm install and it took 25+ min! I know npm can be slow (so I was patient), but wow that was a shock.

[MichMich]

Or we can run NPM in verbose mode.