Ethereum Balance Proxy v1.00

The first release of the Ethereum Balance Proxy!

This proxy converts the Ethereum json rpc method eth_getBalance into REST API with 2 calls:
/ethereum/balance/:address <- gets the latest balance for this address
/ethereum/balance/:address/block/:block <- gets the latest balance for this address at a particular block

The proxy accepts a list of possible upstream ethereum endpoints, confirms that they are viable, healthy and determines if they are archive endpoints or not. Archive endpoints service older blocks in the balance by block api call.

The proxy maybe bypassed for debug purposes and evaluation, by using the ethBalanceProxy ops ... family of calls. Each command skips the upstream manager and balance proxy, directly utilizing the upstream.ethereum.Client.