Add beacon state methods in the RPC protocol

[ajoydas]

Is your feature request related to a problem? Please describe.
Currently in Hobbits, there is no way to get the beacon states from the connected peers. We need the beacon state information in the syncing process for storing the LatestStateRoot, FinalizedStateRoot and JustifiedStateRoot. This is how lodestar uses the beacon state info in the initial syncing process.

Describe the solution you'd like
Add 2 methods in the RPC protocol like Get_Beacon_States

{
    'hashes' : '[]bytes32' 
}

and Beacon_States

{
    'states' : '[]BeaconState`
}

[decanus]

@ajoydas, would you like to create a PR for this?

[ajoydas]

@ajoydas, would you like to create a PR for this?

Yes.