working on tests
invoice item repository test
invoice repository test
Merge pull request #4 from cbyn/chris

Chris
paired with mike mangino
fixed customer repository test
just testing changes
Merge pull request #6 from cbyn/chris

first implementation of relationships for Customer.invoices
Merge pull request #7 from cbyn/chase

Chase
fixed tests for rake
Merge pull request #8 from cbyn/chase

fixed tests for rake
tests for sales_engine class