Display aggregate vote stats in listgovproposalvotes

[shohamc1]

listgovproposalvotes just returns a list of votes of a proposal. There is no way to find aggregate stats such as total number of votes, total number of yes, no and neutral via the RPC, which means users and applications have to write additional scripts to find this information.

listgovproposalvotes should instead return the aggregate stats along with the raw data. This can be achieved with a new argument, which when enabled will return the aggregate stats.

Current

$ ./defi-cli -testnet listgovproposalvotes 'b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1' 'all' 0
[
  {
    "proposalId": "b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1",
    "masternodeId": "dba7c2e1d62e528b38ad3725966945fe7ecfee6339a304fd865a6a6944ab1a00",
    "cycle": 1,
    "vote": "YES"
  },
  {
    "proposalId": "b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1",
    "masternodeId": "0c883a4c9b371d04ffc3afffa0c3f25cf47e019e888742893fdd3ff37afd3500",
    "cycle": 1,
    "vote": "YES"
  },
...

After proposed change

$ ./defi-cli -testnet listgovproposalvotes 'b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1' 'all' 0 true
[
  {
    "proposalId": "b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1",
    "total": 100,
    "yes": 50,
    "no": 30,
    "neutral": 20
  }
]

$ ./defi-cli -testnet listgovproposalvotes
[
  {
    "proposalId": "b1d19f0a1326655148ebdc967dbf0ffcbbf0bb822069737475c7deac3efc9af1",
    "total": 100,
    "yes": 50,
    "no": 30,
    "neutral": 20
  },
  {
    "proposalId": "7025b328f77cfa7f79139ddbbf25a660798b93546ec4879276e05fe31de3b6e6",
    "total": 100,
    "yes": 50,
    "no": 20,
    "neutral": 30
  },
  ...
]

[prasannavl]

Ah, this is neat. Can't break the existing API however. How about making proposalId optional and actually list out all aggregates in one go - this would be a new API, so we don't break existing usage.