we use an environment specific entry for the daoAddress.
Locally we deploy our own, but for rinkeby and other public networks
we use the official entries.
To make deployments easy we store the address in the arapp.json
Allows anybody with the VETO_CONTRIBUTION_ROLE to veto a contribution
and thus prevent that the contribution can be claimed.
So far like the ADD_CONTRIBUTION_ROLE any contributor is allowed to
veto.
