Add option to not copy web fonts

This will (optionally) reduce the size of the SVG and speed things up when no fonts need to be copied.
Thanks to @davidburns573 and @YujiaCheng1996
Fixes #158

src/dom-to-image-more.js

@@ -82,6 +82,7 @@
      * @param {Boolean} options.cacheBust - set to true to cache bust by appending the time to the request url
      * @param {String} options.styleCaching - set to 'strict', 'relaxed' to select style caching rules
      * @param {Boolean} options.copyDefaultStyles - set to false to disable use of default styles of elements
+     * @param {Boolean} options.disableEmbedFonts - set to true to disable font embedding into the SVG output.
      * @param {Object} options.corsImg - When the image is restricted by the server from cross-domain requests, the proxy address is passed in to get the image
      *         - @param {String} url - eg: https://cors-anywhere.herokuapp.com/
      *         - @param {Enumerator} method - get, post
@@ -95,12 +96,13 @@
         options = options || {};
         copyOptions(options);
         let restorations = [];
+
         return Promise.resolve(node)
             .then(ensureElement)
             .then(function (clonee) {
                 return cloneNode(clonee, options, null, ownerWindow);
             })
-            .then(embedFonts)
+            .then(options.disableEmbedFonts ? Promise.resolve(node) : embedFonts)
             .then(inlineImages)
             .then(applyOptions)
             .then(makeSvgDataUri)
@@ -605,6 +607,7 @@
             return node;
         });
     }
+
     function newUtil() {
         let uid_index = 0;