Add product to ocs Version struct

The web ui will announce the backend version in the javascript console
and is supposed to include the product name as well. The version seems
to be a good location for the product field as it already includes the
software edition as well.

internal/http/services/owncloud/ocs/data/capabilities.go

@@ -224,4 +224,5 @@ type Version struct {
 	Micro   int    `json:"micro" xml:"micro"` // = patch level
 	String  string `json:"string" xml:"string"`
 	Edition string `json:"edition" xml:"edition"`
+	Product string `json:"product" xml:"product"`
 }