Factory that cheaply and easily creates BrightID smart contracts for apps

[adamstallard]

We should deploy a factory contract, so that if an app wants to use a template and just change the parameters, they can deploy it more cheaply and easily.

OpenZeppelin already has a factory contract we can use.

See https://medium.com/upstate-interactive/how-to-build-a-contract-factory-that-creates-contract-clones-efcc9619be0b for an example.