Add payment contract functions - deploy and show

[elv-serban]

As a tenant, create a payment contract for revenue splits.

At creation - specify the list of stakeholders: an array of addresses and a corresponding array of shares.
Shares are integers and represent proportions so they don't need to, for example, add up to 100 (but they can, for simplicity).

Examples:

Create a payment contract

./elv-live payment_contract_create 0xc05e0274158442b7d595e5ac6d483d18df8fc93e,0x165b828643eb0fa8a7c6b15330670106169941cc 80,20
Deploy new payment contract

contract_address: '0xcd6c150e4da4a22cdc3d128f4024e039234d6b59'
shares: 100

Show status of payment contract and stakeholders

./elv-live payment_contract_show 0xcd6c150e4da4a22cdc3d128f4024e039234d6b59 0x4c6C3547f81Ef23ED6e6562ab05a598DDdDd140d
Show payment contract status

contract_address: '0xcd6c150e4da4a22cdc3d128f4024e039234d6b59'
shares: 100
released: 0
payees:
  '0xC05e0274158442B7d595E5AC6D483d18DF8fc93e':
    shares: 80
    released:
      _hex: '0x00'
  '0x165B828643eB0fA8A7C6b15330670106169941cc':
    shares: 20
    released:
      _hex: '0x00'

Follow up items (can be done as separate PRs)

• figure out how to call the payment 'releasable' function (currently fails)
• could refine the 'show' output to represent the values with 'decimals' instead of big ints

[elv-preethi]

releasable method was overloaded function.
Followed fix from here:
ethers-io/ethers.js#407
and made formatArguments false. It seems to work now.

./elv-live payment_contract_show 0xcd6c150e4da4a22cdc3d128f4024e039234d6b59 0x4c6C3547f81Ef23ED6e6562ab05a598DDdDd140d
Show payment contract status

contract_address: '0xcd6c150e4da4a22cdc3d128f4024e039234d6b59'
shares: 100
released: 0
payees:
  '0xC05e0274158442B7d595E5AC6D483d18DF8fc93e':
    shares: 80
    released: 0
    releasable: 0
  '0x165B828643eB0fA8A7C6b15330670106169941cc':
    shares: 20
    released: 0
    releasable: 0

@elv-serban

[elv-serban]

Great find!

[elv-wayne]

Looks good, other than allowing shares to be non integer strings. Not sure how much input validation do we need on these contracts

[elv-wayne]

Does the contract check for bad share values?

[elv-preethi]

These are the checks done in constructor:

require(payees.length == shares_.length, "PaymentSplitter: payees and shares length mismatch");
require(payees.length > 0, "PaymentSplitter: no payees");


require(account != address(0), "PaymentSplitter: account is the zero address");
require(shares_ > 0, "PaymentSplitter: shares are 0");
require(_shares[account] == 0, "PaymentSplitter: account already has shares");

[elv-serban]

I added validation for addresses and shares (integers)