Make the goal number function as a 'max disbursement' as well

[pjz]

Default is 'none': take all my tips immediately.

Pertinent to #1050 and #1041

If I set a goal of $100/mo and my incoming tips total more than that, the rest stays in escrow for me for next month, in case my tips drop below the $100 level, or if I change my goal.

Unclear how detailed my view of incoming should be. Possibly all the info, or possibly just 'you're pre-funded for the next N months.'

Also: unclear tax implications.

[ehmatthes]

I like this as a personal choice, on the part of the recipient. I'd want to know if this puts gittip in any legal role as a bank of some sort.

[chadwhitacre]

Re: bank, see #938.

[Changaco]

Closing in favor of #1063.