Add tab-moving key bindings for mac

keymaps/darwin.cson

@@ -29,6 +29,8 @@
   'ctrl-alt-cmd-l': 'window:reload'
   'alt-cmd-i': 'window:toggle-dev-tools'
   'cmd-alt-ctrl-p': 'window:run-package-specs'
+  'ctrl-shift-left': 'pane:move-item-left'
+  'ctrl-shift-right': 'pane:move-item-right'
 
   # Sublime Parity
   'cmd-,': 'application:show-settings'