Fix CI tests (#452)

- Fix lint warning.
- Set the correct electron version in `appveyor.yml`

Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>

appveyor.yml

@@ -14,7 +14,7 @@ environment:
     ELECTRON_NO_ATTACH_CONSOLE: true
     npm_config_disturl: https://atom.io/download/atom-shell
     npm_config_runtime: electron
-    npm_config_target: 0.37.6
+    npm_config_target: 1.1.1
     npm_config_arch: x64
   matrix:
     - nodejs_version: 6.1.0

lib/gui/os/open-external/directives/open-external.js

@@ -17,7 +17,6 @@
 'use strict';
 
 const electron = require('electron');
-const os = require('os');
 
 /**
  * @summary OsOpenExternal directive