Add missing -spec suffix to desktop capturer spec

spec/api-desktop-capturer-spec.js

@@ -0,0 +1,17 @@
+var assert, desktopCapturer;
+
+assert = require('assert');
+
+desktopCapturer = require('electron').desktopCapturer;
+
+describe('desktopCapturer', function() {
+  return it('should returns something', function(done) {
+    return desktopCapturer.getSources({
+      types: ['window', 'screen']
+    }, function(error, sources) {
+      assert.equal(error, null);
+      assert.notEqual(sources.length, 0);
+      return done();
+    });
+  });
+});