Renames k8s-render-demo to gifinator

[ghchinoy]

Minor change to import to correct make errors:

$ make
go build -o frontend/frontend ./frontend
go build -o gifcreator/gifcreator ./gifcreator
gifcreator/gifcreator.go:38:2: cannot find package "github.com/GoogleCloudPlatform/k8s-render-demo/internal/gcsref" in any of:
...