Using Pool Issuance balance in `PoolFactor`

[yellowbean]

There 3 type of balance for asset

• OriginBalance -> the asset face value
• IssuanceBalance -> the current balance of asset when it "entered" in SPV
• CurrentBalance -> which is changing during the projection of cashflow .

Current way to calculate the pool factor :

• current balance as a nominator
• if there is a stat balance map:
  • use balance value from field "issuance balance"
  • if not , just use OriginBalance as default, which is NOT the issuanceBalance

[yellowbean]

New logic:

always use issuanceBalance to calculate originalPoolBalance

https://github.com/yellowbean/Hastructure/pull/90/commits/c971f69ce441cd36346072738893a494179f00c5