Added test for and implementation of Invoice.random
added test for and implementation of Invoice.find_by_id
added tests and implementation for finding an invoice by customer id and merchant id
Added test and implementation for finding and invoice by stats
Added test for and implementation of finding invoice by created_at date
added test for and implementation of Invoice.find_by_updated_at
renamed methods
Added tests for and implentation of finding all invoices by merchant it, customer id, and created_at
added test for and implementation of finding all invoices by created and updated dates
added test for and implementation of Item.random
added more tests and implemented more stuff for items
added tests for and implentations of finding all items by name, unit price, merchant id
Added tests and implementation for finding items by created and updated date
added stuff to items..
committing changes??
blah
merging item methods