zAuction bid data management

zAuction API code and build instructions can be found at https://github.com/zer0-os/zAuction-API The zAuction API is a service helping access storage of signed bid messages. It helps encode bid data for signing, and stores the user-signed message after verification that the user has signed valid data that can be submitted in a successful transaction. It can retrieve bids for an NFT, a list of NFTs, and for an account. The intended bid flow is: User chooses amount to bid on NFT -> Client sends data to 'Encode bid', which returns the data to sign -> User signs data with their locally stored private key -> Client sends signed data to 'Create bid', which validates and stores the bid. Acceptance of bids happens on-contract and does not go through the API.