Don't bail out if image doesn't exist locally

The backend will figure out if we have the image or not, otherwise will
atempt to pull if not there.

Skip retrieve integration test with img as its not supported.

pkg/compiler/backend/simpledocker.go

@@ -175,7 +175,7 @@ func (*SimpleDocker) ExportImage(opts compiler.CompilerBackendOptions) error {
 		return errors.Wrap(err, "Failed exporting image: "+string(out))
 	}
 
-	Info(":whale: Exported image:", name)
+	Debug(":whale: Exported image:", name)
 	return nil
 }