(Feature) Top delegates

[Agupane]

Depends on #41
Depends on #42
Closes #58

Description

Let the user to get the top "x" transcoders based on their ROI value

ROI Calculation:

Represent the amount of LPT that a delegator will obtain each round he bonds to a delegator.
The return of investments (ROI) is calculated always for the next round. It's calculated using a totalBonded stake of 1000, so, it's the value that a delegator will obtain for the next round is he bonds 1000 LPT to that transcoder

ROI = rewardsToDelegatorsForNextRound*delegatorParticipationInBondedStakeRatio

RewardsToDelegatorsForNextRound = delegateRewardsForNextRound * (1-delegateRewardCut)

DelegateRewardsForNextRound = mintedTokensForNextRound * delegateParticipationInTotalBonded

Example:

http://localhost:4040/api/delegates/top/5

Result:
[
    {
        "id": "0xf1ee89810f4441b025d2d42ff58a0cdc4d797310",
        "totalStake": "692281940372333711643",
        "roi": "80.98202110272603210234"
    },
    {
        "id": "0xcfa2a70fdf74ebda788eeb1498425ceb0630e1cb",
        "totalStake": "5088712707818879776558",
        "roi": "58.92400408443955878542"
    },
    {
        "id": "0x345551571c5ef20111c6168b9a498dfb836e7c09",
        "totalStake": "41434955154102026869031",
        "roi": "5.31439249639314928832"
    },
    {
        "id": "0xdac817294c0c87ca4fa1895ef4b972eade99f2fd",
        "totalStake": "48559774660215370973441",
        "roi": "4.47921732786657223192"
    },
    {
        "id": "0xbd91c9df3c30f0e43b19b1dd05888cf9b647b781",
        "totalStake": "83835447024235519002350",
        "roi": "3.62773631538480508463"
    }
]

[mariano-aguero]

@Agupane I think we need to do:

• Fix the build
• Fix the conflicts
• Try to rebase the/merge development