Built-in logger 'logger.debug' doesn't print anything in Node 8

[tiaod]

Before Node 8, console.debug is undefined.

Now using node v6.11.2 (npm v3.10.10)      
> console.debug('hello')                                     
TypeError: console.debug is not a function            

It will default to baseLogger["info"]
https://github.com/ice-services/moleculer/blob/943ce4724b054284c1051ebad7244e0755bd8759/src/logger.js#L87
However, in Node 8, console.debug is exposed and doesn't print anything.

Now using node v8.4.0 (npm v5.3.0)       
> console.debug                   
[Function: debug]                 
> console.debug('hello world')    
undefined                         
> 

So the logger.debug is not working anymore.

Maybe relate to: nodejs/node#12675

[icebob]

Thank you!