The contribution contract implements an ERC721 interface which
represents any contribution.
The contributions are non-fungible (as opposed to the Kredits tokens)
and can be not be transferred. The contract stores the history of any
contribution.
Contributions can be claimed which will issue the Kredits tokens to the
contributor.
This is an early implementation and misses some access control and
probably more things.
This allows to manage different contracts (Token, Collaborator, etc.)
with one registry.
The registry serves as main source for all contracts and versions.
Versions are independently deployed and added to the registry. From
there the proxy contract's implementation can be upgraded to the new
version.
Currently no access control is implemented.
