* initial feature scaffolding
* implement interest keeper logic
* basic AccrueInterest
* accrue interest on borrow
* update borrow index formula
* update sample reserve factor
* move AccrueInterest to begin blocker
* refactor interest rate updates for accrue interest
* use interest rate model from store
* refactor begin blocker state machine
* add reserve factor to interest model params
* update comment
* store money market instead of interest rate models
* update test suite
* use BorrowedCoins store key
* update public functions and alias
* unit tests, keeper test scaffolding
* demo panic
* address revisions
* add 'normal no jump' test case
* spy = 1 + borrow rate
* update comment
* APYToSPY unit test
* per user borrow index list
* interest keeper test
* test: interest applied on successive borrows
* varied snapshot times
* test: multiple, varied snapshots
* address revisions
* add pending interest before validating new borrow
* update makefile
* address revisions
* fix test
