Sync bounties

GRT for syncing a subgraph first

A developer who wants a subgraph indexed escrows GRT in a contract. The first indexer to allocate to the deployment, sync it and present a proof of indexing to the protocol has earned it, and anyone can then send it on: the contract reads the allocation from the SubgraphService and pays that indexer, whoever presses the button. Nothing here is held or decided by Lodestar. The contract is verified, and unaudited. Developers post from the page for their subgraph.