add some re-usable APIs

define some pending/ready helpers as static constants on orm.Spawner

allows treating orm.Spawner the same as Spawner wrappers,
as long as `.active` etc. checks are performed first

jupyterhub/orm.py

@@ -135,6 +135,16 @@ class User(Base):
     id = Column(Integer, primary_key=True, autoincrement=True)
     name = Column(Unicode(255), unique=True)
 
+    # properties on the spawner wrapper
+    # some APIs get these low-level objects
+    # when the spawner isn't running,
+    # for which these should all be False
+    active = running = ready = False
+    pending = None
+    @property
+    def orm_spawner(self):
+        return self
+
     _orm_spawners = relationship(
         "Spawner",
         backref="user",