Emit events on upgradeable contract initialization

[cam-schultz]

Context and scope
In order to glean the initialization parameters and contract type from a contract creation transaction, the deployed bytecode must be mapped to source code (i.e. contract verification). This is an extra necessary layer on top of the on-chain activity to expose this information. Further, for older contracts that have not been verified, it can be difficult to find the exact version of the source code.

Discussion and alternatives
Instead, we should emit a unique event containing important contract parameters at initialization time. This would also allow changes to the contract conducted via upgrade to be tracked (assuming of course that the initialization event remains similar)