Streamline setting up an installment plan when creating a pledge

Streamline setting up an installment plan when creating a pledge so that you can more easily add pledges. Possible areas of friction:

• The majority of donors intend to make one payment, and don't have a specific date in mind. As a general rule of thumb, the system could default to a single payment X months after the pledge is made. That way users only need to update the installment plan if they know more details.

• Having installment setup on a separate tab is hard to notice