Move project URL to electronjs.org (#100)

base/base_header.ts

@@ -1,5 +1,5 @@
 // Type definitions for Electron <<VERSION>>
-// Project: http://electron.atom.io/
+// Project: http://electronjs.org/
 // Definitions by: The Electron Team <https://github.com/electron/electron>
 // Definitions: https://github.com/electron/electron-typescript-definitions