Make sandbox APIs more compatible with normal renderers

- Expose remote shortcuts for the `fs`, `os` and `child_process` modules.
- Expose the `url` and `timers` modules(the browserify versions)
- Add `process.crash` and `process.platform`

electron.gyp

@@ -441,7 +441,13 @@
         'sandbox_args': [
           './lib/sandboxed_renderer/init.js',
           '-r',
-          './lib/sandboxed_renderer/api/exports/electron.js:electron'
+          './lib/sandboxed_renderer/api/exports/electron.js:electron',
+          '-r',
+          './lib/sandboxed_renderer/api/exports/fs.js:fs',
+          '-r',
+          './lib/sandboxed_renderer/api/exports/os.js:os',
+          '-r',
+          './lib/sandboxed_renderer/api/exports/child_process.js:child_process'
         ],
         'isolated_args': [
           'lib/isolated_renderer/init.js',