Move registerFonts back

lib/settings/validate-settings.js

 var fs = require("fs"),
     path = require("path"),
     mkdirp = require("mkdirp"),
-    Canvas = require("canvas"),
     _ = require("underscore");
 
 module.exports = function(settings) {
 
       try {
         fs.accessSync(font.file);
-        Canvas.registerFont(font.file, _.pick(font, "family", "weight", "style"));
       } catch(e) {
         return console.warn("Font file " + font.file + " does not exist or is not readable.");
       }