Add ctrl-pageup and ctrl-pagedown Win32 bindings

keymaps/win32.cson

@@ -10,6 +10,8 @@
   'ctrl-alt-i': 'window:toggle-dev-tools'
   'ctrl-alt-p': 'window:run-package-specs'
   'ctrl-alt-s': 'application:run-all-specs'
+  'ctrl-pageup': 'pane:show-previous-item'
+  'ctrl-pagedown': 'pane:show-next-item'
 
   # Sublime Parity
   'ctrl-N': 'application:new-window'