Change package entry for electron-builder. See https://github.com/mattermost/desktop/pull/138#discussion_r63242703

gulpfile.js

@@ -193,7 +193,7 @@ function makePackage(platform, arch, callback) {
     icon: 'resources/icon',
     "version-string": {
       CompanyName: packageJson.author.name,
-      LegalCopyright: 'Copyright (c) 2015 - 2016' + packageJson.author.name,
+      LegalCopyright: 'Copyright (c) 2015 - ' + new Date().getFullYear() + ' ' + packageJson.author.name,
       FileDescription: packageJson.description,
       OriginalFilename: packageJson.productName + '.exe',
       ProductVersion: packageJson.version,

package.json

@@ -23,7 +23,7 @@
     "package": "gulp package",
     "package:windows": "gulp package:windows",
     "package:osx": "gulp package:osx",
-    "package:linux": "gulp build && build --platform linux --arch all -d deb",
+    "package:linux": "gulp build && build --platform linux --arch all",
     "package:all": "gulp package:all",
     "prettify": "gulp prettify",
     "installer": "node ./script/installer.js"
@@ -34,7 +34,7 @@
     "babel-preset-react": "^6.5.0",
     "chromedriver": "^2.20.0",
     "del": "^2.2.0",
-    "electron-builder": "3.20.0",
+    "electron-builder": "5.2.1",
     "electron-connect": "^0.3.7",
     "electron-packager": "^7.0.1",
     "electron-prebuilt": "0.37.8",
@@ -63,7 +63,8 @@
     "app-bundle-id": "com.mattermost.desktop",
     "app-category-type": "public.app-category.productivity",
     "linux": {
-      "synopsis": "Mattermost Desktop"
+      "synopsis": "Mattermost Desktop",
+      "target": "deb"
     }
   },
   "directories": {