started on expense accounts.

migrator/migrations/1527534504-DOWN-create-default-expense-account.sql

@@ -0,0 +1,5 @@
+-- 1527534504 DOWN create-default-expense-account
+
+alter table vendors drop column default_expense_account;
+
+drop table invoices_expense_accounts;

migrator/migrations/1527534504-UP-create-default-expense-account.sql

@@ -0,0 +1,5 @@
+-- 1527534504 UP create-default-expense-account
+
+alter table vendors add column default_expense_account INT;
+
+create table invoices_expense_accounts (id serial primary key, invoice_id int references invoices(id), expense_account_id int not null, amount decimal not null);