Allow user to specify custom kaniko image
Allow user to specify custom kaniko image

fixes #1586, previously we were using the default image instead of the image passed in through the config.

GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold,GoogleContainerTools/skaffold