Add Invoices Section

[yassinrais]

• [x] Create Tables
• [x] Create/Update/Delete Invoices
  • [x] Discount
  • [ ] Tax's
  • [x] Customer View (UI)
• [ ] Add Date filtering, Search, Field selection
• [ ] Generate PDF ( Create Workers )
• [ ] Download PDF / Many PDF (zip)
• [x] Clone Invoices
• [ ] Recurring invoices
• [ ] Send Quotes by mail

[yassinrais]

• [ ] Tests