Use correct tag for launcher image

[rmohr]

Use the launcher image and tag, as specified on the commandline, instead
of a hardcoded launcher image.

Fixes #245

[rmohr]

Functional tests are passing.

[davidvossel]

Regression tests are failing because not all references to NewTemplateService have not been updated to take multiple arguments.

NewTemplateService is referenced quite a few places.

grep -r -n "NewTemplateService" .
./cmd/virt-controller/virt-controller.go:52:	templateService, err := services.NewTemplateService(*launcherImage)
./pkg/virt-controller/watch/migration_test.go:81:		templateService, _ := services.NewTemplateService("kubevirt/virt-launcher")
./pkg/virt-controller/watch/migration_test.go:114:		templateService, err := services.NewTemplateService("whatever")
./pkg/virt-controller/watch/migration_test.go:781:	temlateService, err := services.NewTemplateService("whatever")
./pkg/virt-controller/watch/vm_test.go:63:		templateService, _ := services.NewTemplateService("kubevirt/virt-launcher")
./pkg/virt-controller/watch/vm_test.go:96:			temlateService, err := services.NewTemplateService("whatever")
./pkg/virt-controller/watch/vm_test.go:150:			temlateService, err := services.NewTemplateService("whatever")
./pkg/virt-controller/services/vm_test.go:56:		templateService, _ := NewTemplateService("kubevirt/virt-launcher")
./pkg/virt-controller/services/template.go:144:func NewTemplateService(launcherImage string) (TemplateService, error) {
./pkg/virt-controller/services/template_test.go:37:	svc, err := NewTemplateService("kubevirt/virt-launcher")

[davidvossel]

Is this patch a stop gap to moving the migration script into a separate container? It seems a bit weird to be overloading the virt-handler container with this logic, but it's possible there is some context to this I'm missing.

[rmohr]

@davidvossel There is no real reason. I think splitting it makes sense.

[davidvossel]

this looks good to me. we can address splitting out migrations into a separate container later.