Batched flip status handling in the gateway

[stonier]

This started to get implemented in get_multiple_flip_request_status() in gateway.py, but isn't actually used anywhere.

The status is retrieved in three places:

• When you try to send a flip, just checks to see if its not already on the server
• At the start of updating the flipped connections, check to see if a resend is required
• At the end of updating the flipped connections, check to see if any have changed

In all these cases, it goes via the singular get_flip_request_status to get the status, which means for loops everywhere. This batched retrieval hasn't been utilised.

This is an issue to remind us that we could do so and save alot of looping.

[stonier]

Actually, this has all been implemented nicely by piyush in a700fdce and redirects to the batched call.

def get_flip_request_status(self, remote_rule):
        status = self.get_multiple_flip_request_status([remote_rule])
        return status[0]