ListSearch#all uses self's collection

rather than needing something to be passed in
Memoize SalesEngine in CustomerRepoTest
Add example of how to pull CSV up to SalesEngine
Fix SalesEngine which makes the test break in the correct place
Refactor csv responsibility to sales_engine, update tests
stuff
Merge branch 'josh-changes' of github.com:a6ftcruton/sales_engine into josh-changes
changed invoice_repo
Update invoice item tests
Fix merge conflict in sales_engine
items done
Update merchant tests
Fix merge conflict
transaction changed
integration tests passing
added relationship between customers and invoices
four relationships done
Module test, hours of frustration
more integration tests, getting ready to merge with jim
Fix merge conflict in integration_test