implement quit api. indicate if backend is offline

oml/api.py

@@ -9,7 +9,6 @@ import os
 import ox
 from oxtornado import actions
 
-
 import item.api
 import user.api
 import update
@@ -77,3 +76,20 @@ def autocompleteFolder(data):
         'items': ox.sorted_strings(folders)
     }
 actions.register(autocompleteFolder, cache=False)
+
+def quit(data):
+    '''
+        takes {
+        }
+        returns {
+        }
+    '''
+    '''
+    import server
+    server.shutdown()
+    '''
+    import settings
+    subprocess.Popen([os.path.join(settings.base_dir, 'ctl'), 'stop'],
+            close_fds=True, start_new_session=True)
+    return {}
+actions.register(quit, cache=False)