Add the cash script for keeping track of cash on hand

I can't seem to run tests, but these should pass based on other test
suites I've seen.
Switch to using an output formatter for the currency and date formatting

I was having some trouble with no method errors on the data formating.
Instead of troubleshoot that, I just wrote the output formatter. I
should review this later and test the formats instead. Extending Number
and Date would be nicer.
Merge pull request #566 from jhubert/master

Adds a simple script for keeping track of cash on hand vs burn rate and giving a summary