Drop payout fee

It turns out that Balanced isn't actually charging us for payouts(!). Here's my interaction with support:

> Hi there! :)
> 
> It looks like I'm not being charged for ACH credits. Can you confirm? What's the story? I'm expecting to be charged 25¢ each but all the invoices I've checked say $0 for credits.
>
>
> chad

And the reply:

> Hi Chad,
> 
> It's because you're special :) Gittip doesn't get charged fees for credits based on your agreement with us when you got started with Balanced.
> 
> Thanks,
> 
> Manisha

As a result (and this came up at the lightening talk AMA I did at PyOhio last weekend), we should pass this on to our users and drop the payout fee. I don't think we should worry about refunding, though that would certainly be a thing.