Devise method for guaranteeing contract logic

[danoctavian]

Any vendor created contract must be known to use the same implementation as the one publicly available.

One possibility is to make vendor contracts be generated by a contract factory which is trusted to hold the correct bytecode for the contract.

This is similar to the pattern used by uniswap https://docs.uniswap.io/smart-contract-api/factory

This is how to create upgradeable contracts using a factory

https://github.com/OpenZeppelin/openzeppelin-sdk/tree/master/examples/creating-instances-from-solidity