Imports of package testing

PathSynopsis
github.com/google/cadvisor/containerPackage container defines types for sub-container events and also defines an interface for container operation handlers.
github.com/google/cadvisor/info/v1Types used for docker containers.
github.com/stretchr/testify/mockPackage mock provides a system by which it is possible to mock your objects and verify calls are happening as expected.