Created Cancel call in webmvc

# Conflicts:
#	eShopOnContainers-ServicesAndWebApps.sln
#	src/Services/Basket/Basket.API/Controllers/BasketController.cs
#	src/Services/Basket/Basket.API/Startup.cs

When the previous page is the MainView, switching from mock to real
services will force re-authentication by navigating to the LoginView.

# Conflicts:
#	eShopOnContainers-ServicesAndWebApps.sln

Because of the using blocks, these one line methods need the async
modifier so that the that async state machiner is created. Otherwise, if
the method does not complete synchronously, the connection is closed
before the database has returned its results.

The methods that return collections should return
Task<IEnumerable<dynamic>> not Task<dynamic>