NPM installation issues 
Warnings at installation time.  

<img src="https://user-images.githubusercontent.com/1205471/82779214-72bae780-9e08-11ea-85d1-dac56e907f9b.jpeg" width="275"/>

# Current environment
Module | Version
-- | --
Node.js | 12.16.3
NPM | 6.14.5
homebridge | 1.1.0
Alpine Linux (running in a Docker on a Synology) | 3.11.6
