Deprecated corslite and polyline warnings during install

[Nikhil VJ]

On installation command sudo npm install, saw these warning messages:

npm WARN deprecated corslite@0.0.6: This module is now under the @mapbox namespace: install @mapbox/corslite instead
npm WARN deprecated polyline@0.0.3: This module is now under the @mapbox namespace: install @mapbox/polyline instead
...
npm WARN optional Skipping failed optional dependency /chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.2.9
npm WARN optional Skipping failed optional dependency /watchify/chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.2.9

Don't know what to do about the fsevents part, but corslite and polyline I was able to install by:

sudo npm install @mapbox/corslite
sudo npm install @mapbox/polyline

But I saw this output:

├── @mapbox/corslite@0.0.7  extraneous
├── @mapbox/polyline@1.1.0  extraneous
└── file-saver@1.3.8 

Not so sure now whether these were needed or not, but I got the frontend running properly now. In the console network monitor, i see corslite.js playing a prominent role so it may be important. (change services > path in src/leaflet_options.js to make it poll your osrm-backend instead of the web!)

Also, it might be worth mentioning that I had to sudo npm install instead of just npm install to avoid all the error messages.