Added multicurrency support

src/tjts5901/app.py

src/tjts5901/currency.py

src/tjts5901/models.py

src/tjts5901/templates/addItem.html

src/tjts5901/templates/listBid.html

src/tjts5901/templates/money-tag.html

src/tjts5901/templates/view.html

src/tjts5901/views.py