updated customer test to incluce empty array check
Merge pull request #14 from cbyn/chris

updated customer test to incluce empty array check
moved csv reading out of repos and up to sales_engine
new transaction_repo test
changed customer test
updated test
customer repo test
tests for invoice and invoice_repo
fixed typos in sales_engine and csv_reader and retested customer.invoices
transaction.invoice implemented and tested
work in progress for invoice relationships
Merge pull request #15 from cbyn/chris

Chris
new tests and merge conflict