Fix macOS build

.gitignore

@@ -1,3 +1,4 @@
 node_modules/
 dist/
-package/
+package/
+.DS_Store

src/desktop/build.darwin.js

@@ -1,5 +1,5 @@
 const packager = require('./build.package.js');
-const createDMG = require('electron-installer-dmg');
+const { createDMG } = require('electron-installer-dmg');
 
 async function build(arch) {
     await packager.app('darwin', arch);
@@ -9,7 +9,14 @@ async function build(arch) {
         title: 'Certbox',
         icon: 'src/icons/certbox.icns',
         format: 'ULFO',
-        out: 'package/artifacts'
+        out: 'package/artifacts',
+        background: 'src/icons/dmg_bg.png',
+        contents: (opts) => {
+            return [
+                { x: 469, y: 239, type: 'link', path: '/Applications'},
+                { x: 185, y: 239, type: 'file', path: opts.appPath}
+            ];
+        }
     });
     await packager.exec('mv', ['package/artifacts/Certbox.dmg', 'package/artifacts/certbox_macOS_' + arch + '.dmg']);
 }