Upgrade EventListener so it isn't reliant on user passing truffle-contract objects

[satello]

EventListener relies on truffle-contract objects to watch event logs. This is easy for us to use but isn't particularly flexible as a util and will need to be generalized if we want to make it until a self contained tool kit.

Potential options:

• Parse Tx/Blocks directly like what is done here. We could fork this repo and extend it to fit our multi contract/ multi handler needs if this route is chosen.
• Investigate using filters with raw web3. User will need to pass contract abi.
• Create some sort of very general base contract wrapper for the EventListener that still uses truffle contract but doesn't force the user to have to know about it. (i.e. it needs to be passed a contracts/Implementations. This seem restrictive outside of our codebase however.