Add RPCs which will be useful for testing

[mhchia]

This rpc should be able to list a node's peers in shard

Usage:

$ ./sharding-p2p-poc -client listshardpeer 0
[peer0, peer1, ...]

[mhchia]

Should add RPCs again:

• GetConnection() returns connections
• GetPeer(topic string) returns peerIDs
• SyncShardPeer(rpcAddr string, peerID peer.ID, shardIDs []ShardIDType) returns shardPeers
• SyncCollation(peerID peer.ID, shardID ShardIDType, period int, collationHash string) returns collation
• RemovePeer()
• RemovePeerConnection()

[jrhea]

@mhchia what do you want returned for listshardpeer?

A list of peers with dups removed?

$ ./sharding-p2p-poc -port=10000 -rpcport=13000 -client listshardpeer 2 3 
[PEER_1,PEER_2]

A JSON object that contains a list of peers for each shard?

$ ./sharding-p2p-poc -port=10000 -rpcport=13000 -client listshardpeer 2 3 
{"shardCollations_2":[PEER_1,PEER_2],"shardCollations_3":[PEER_2,PEER_3]}

[mhchia]

@jrhea

I'd prefer

$ ./sharding-p2p-poc -port=10000 -rpcport=13000 -client listshardpeer 2 3 
{"2":[PEER_1,PEER_2],"3":[PEER_2,PEER_3]}

in this case, since listtopicpeer does roughly the same thing as your second example already. Thank you:)

[mhchia]

Fixed by #104