Modified plugin to allow for multiple suppliers per product
correct table name from products_suppliers to spree_products_suppliers
Revert "correct table name from products_suppliers to spree_products_suppliers"

This reverts commit f40e4fd6d230556020b475d5b6b4e927285e6076.
correct index name
Each supplier-product link holds a SKU, cost price, and shipping cost
Make multiple_suppliers_per_product migration script reversible
Set table name for Spree::Supplier manually
set_table_name in Spree::Supplier was not actually necessary