Feature/small refactors

[alexcos20]

Changes proposed in this PR:

• ERC721: add new function setMetaDataState (allows publisher to change state using a cheap function)
• ERC721: added MetadataState event so Aquarius can track for state changes
• Remove all indexed strings in events (a string should never be indexed in a event)
• Adding more details to some events (ERC721, Dispenser, ERC20)
• Proper use of tokenURI in ERC721

@mihaisc - do you need anything else for the graph?

[mihaisc]

I'd say we are good, didn't find anything else.

[alexcos20]

Still needs some changes on the pool side, we have some view functions with events and we are missing events for fees. WIP
All good

[mihaisc]

can we rename feeManager (from erc20) , from my understanding this is not related to fees, this is the account where the payments are collected so ...something like paymentCollector (or a better suggestion )