[Finishes #81547692] List All Invoices
-List each invoices number, date, hospital, and total amount
-Show an invoice when you click on an invoice number in Invoices index view
-Use eager loading to reduce number of database queries
-Style table
-Sort invoices by invoice number descending
-Extend height of form to allow a maximum of 3 parts
-fix ng-model attributes on New Invoice form so that calculateParts function
calculates correctly