dump transfers for debugging when payin fails
failing test for null transfers
don't make null transfers
failing test for negative transfers
don't make negative transfers
don't fetch the `Customer` when we don't actually need it
update tests
update test fixtures
add log message for debugging
failing test for `transfer_tips()`
fix `transfer_tips()`
replace foreman with honcho
add `./env/bin` to `$PATH`
refactor
run payday in the background and tail the log
better error message when exchange fails
fix test
update test to detect another bug
fix `payin()` to flag which participants we actually have card holds for
fix minor bug in `update_stats()`