Fixes for appveyor build: path formats, correct electron binary

Gruntfile.js

@@ -351,8 +351,9 @@ module.exports = function(grunt) {
       var failure;
 
       var Application = require('spectron').Application;
+      var electronBinary = process.platform === 'win32' ? 'electron.cmd' : 'electron';
       var app = new Application({
-        path: path.join(__dirname, 'node_modules', '.bin', 'electron'),
+        path: path.join(__dirname, 'node_modules', '.bin', electronBinary),
         args: [path.join(__dirname, 'main.js')],
         env: {
           NODE_ENV: environment

appveyor.yml

@@ -12,11 +12,11 @@ install:
 
 build_script:
   - yarn run generate
-  - ./node_modules/.bin/build --em.environment=%SIGNAL_ENV% --publish=never
+  - node_modules\.bin\build --em.environment=%SIGNAL_ENV% --publish=never
 
 test_script:
-  - ./node_modules/.bin/grunt test-release:win
+  - node_modules\.bin\grunt test-release:win
-  - yarn test
+  - node_modules\.bin\grunt test
 
 artifacts:
   - path: dist/*.*