Improve "account_activities" DB table structure

#475

db/migrate/20170506155009_rename_account_activity_log_pricelist_id_to_price_id.rb

@@ -0,0 +1,6 @@
+class RenameAccountActivityLogPricelistIdToPriceId < ActiveRecord::Migration
+  def change
+    rename_column :account_activities, :log_pricelist_id, :price_id
+    add_foreign_key :account_activities, :prices
+  end
+end

db/migrate/20170506162952_add_account_activity_account_id_foreign_key.rb

@@ -0,0 +1,6 @@
+class AddAccountActivityAccountIdForeignKey < ActiveRecord::Migration
+  def change
+    change_column :account_activities, :account_id, :integer, null: false
+    add_foreign_key :account_activities, :accounts
+  end
+end

db/migrate/20170506205356_add_account_activity_invoice_id_fk.rb

@@ -0,0 +1,5 @@
+class AddAccountActivityInvoiceIdFk < ActiveRecord::Migration
+  def change
+    add_foreign_key :account_activities, :invoices
+  end
+end

db/migrate/20170506205946_add_account_activity_bank_transaction_id_fk.rb

@@ -0,0 +1,5 @@
+class AddAccountActivityBankTransactionIdFk < ActiveRecord::Migration
+  def change
+    add_foreign_key :account_activities, :bank_transactions
+  end
+end