Make the contracts upgradeable

[fadeev]

Remove constructor, use initialize, instead.

[fadeev]

Add this to initialize:

I'm now thinking that with universal NFT/FT we can streamline the deploy process by adding universal contract address as one of the constructor parameters with deploying a connected contract. The idea is you should always deploy the universal contract first, because it's a single required component, and then deploy connected contracts. This way connected-set-universal task will no longer be required. It still makes sense to keep it as contract addresses may change, but you wouldn't need to set manually it after deploying a connected contract.