Uninstall registry key needs unique identifier

Currently only the product name is used for the uninstall registry key (PackageManagerCorePrivate::registerPath()).
In case there are several versions installed in parallel or there is a product name clash a newer installation will overwrite the entry for the already existing installation.
At least the version number should be added to the key name. Or even better use a GUID: "The values are stored in a subkey identified by the application's product code GUID."
see https://msdn.microsoft.com/en-us/library/aa372105%28v=vs.85%29.aspx