Allow users to accept only xDai Payments

Initial plan was to make payments in half xDai (stable coin) and half HNY token. Due to the slippage and timing of gnosis safe signers, HNY value can be too variable. It has been expressed that some payees will just exchange for xDai again due to current market trends. Keeping payments in pure xDai makes it simpler to send airdrop payments throughout the day without timing gnosis safe signers. This does NOT effect the HNY buy back in the 1Hive treasury portion of our budget. Only payments.