Fix array indices in cash.coffee regex match

Previously, the `amount` variables were being set to `cash.set_on_hand msg.match[3]`, but the `msg.match` array only contains 3 items, so `amount` was being set to `undefined` since JS/CS arrays are zero-indexed.
Merge pull request #1254 from scooter-dangle/patch-1

Fix array indices in cash.coffee regex match