Make console.log and console.warn instructions optional

[BrightSoul]

Hi and thanks very much for this library!
I'd like to exclude the console.log and console.warn instructions since they're polluting the console with messages.

NoSleep.js/src/index.js

Line 80 in 1d15cc8

console.log("Wake Lock active.");

A configuration option would be enough:

const noSleep = new NoSleep({ silent: true });

Do you accept pull requests?