Staging testnet-phase1 subgraph

This subgraph is used by the team for testing purposes. Find the npm package here:
https://www.npmjs.com/package/@graphprotocol/staging-testnet-subgraph

This package has it's own set of contracts, separate from the testnet subgraph we use for the indexers.

v0.3.1-beta

One field was added to Channels - non breaking

Update to our v0.3.1 npm package

Beta

Beta release. Notes:

• Starts at v0.3.0-beta , so that it is in sync with contracts and our contract npm package, @graphprotocol/contracts
• Beta network is running on kovan
• Subgraph endpoint is https://thegraph.com/explorer/subgraph/graphprotocol/graph-network-beta
• Addresses can be found in the npm package https://www.npmjs.com/package/@graphprotocol/contracts