YIP: Add RageQuit Functionality

Link to forum: https://forum.yam.finance/t/yip-add-ragequit-functionality/588

Basic Summary Develop a function that allows YAM to be redeemed for a pro rata portion of the Treasury.

Abstract A core value proposition for YAM has always been the unique value of our growing Treasury model. While it has been assumed that YAM value would be linked to the Treasury, this proposal would make it official that YAM will be backed by the Treasury and immediately signal a price floor.

Motivation With market volatility and a complex story to tell (elastic finance), YAM price has fallen significantly since launch. This function would create a hard price floor, as arbitrage would exist if the Treasury ever exceeded market cap. It also creates a clear story that YAM holders are entitled a portion of the Treasury. (While not widely used, YFI launched with a burn mechanism that created narratives about how YFI holders are entitled to Yearn revenue and immediately established a price floor.) A vote For would immediately signal that this will become official, even if it is not yet developed, thus creating an immediate price floor based on our rapidly growing Treasury value.

Specifications Mechanisms to be developed further in discussion with the community. This initial vote is to first determine officially whether we should or should not develop this function. This does not preclude other solutions, such as staking, from being proposed or developed. (RageQuit was originally named by MolochDAO. This proposal uses the name as a temporary shortcut; the official naming can be decided later with the community.)