Remove lends and loans from the store on zeroing out

[MikeHathaway]

• Remove Lend and Loan entities from the store when they zero out their attributes.
• Add new _handleBucketBankruptcy function

[EdNoepel]

I'm not excited about removeLendFromStore and removeLoanFromStore, especially the naming. I was tempted to recommend they be included in updateBucketLends and updateAccountLoans, but I see why that coupling would be undesirable.

How about we rework these methods as saveOrRemoveLend and saveOrRemoveLoan? The caller calls this method in lieu of entity.save, the method handles the branch, and no return value is needed.

[MikeHathaway]

I'm not excited about removeLendFromStore and removeLoanFromStore, especially the naming. I was tempted to recommend they be included in updateBucketLends and updateAccountLoans, but I see why that coupling would be undesirable.

How about we rework these methods as saveOrRemoveLend and saveOrRemoveLoan? The caller calls this method in lieu of entity.save, the method handles the branch, and no return value is needed.

Updated as recommended in a4ad178

I had originally just done the removal in those methods which worked with minimal changes but then I became concerned about the maintainability of that approach especially with the dependency on method ordering for updateBucketLends and updateAccountLends

[EdNoepel]

Much thanks; LGTM.