Rename some listeners to `wait_until_`.

Mainly login and ready listeners.

discord/client.py

@@ -478,7 +478,7 @@ class Client:
     # listeners/waiters
 
     @asyncio.coroutine
-    def wait_for_ready(self):
+    def wait_until_ready(self):
         """|coro|
 
         This coroutine waits until the client is all ready. This could be considered
@@ -488,12 +488,12 @@ class Client:
         yield from self._is_ready.wait()
 
     @asyncio.coroutine
-    def wait_for_login(self):
+    def wait_until_login(self):
         """|coro|
 
         This coroutine waits until the client is logged on successfully. This
         is different from waiting until the client's state is all ready. For
-        that check :func:`discord.on_ready` and :meth:`wait_for_ready`.
+        that check :func:`discord.on_ready` and :meth:`wait_until_ready`.
         """
         yield from self._is_logged_in.wait()