Allow the code path which creates the DLNA.ORG_PN string to be entered if the renderer is configured to use accurate DLNA.ORG_PN.
Allow the DLNA.org content features header value to be set correctly when the method which sets necessary instance variables had not been called yet. This will be refactored in a following commit.
Refactor the DLNA.ORG_OP and DLNA.ORG_PN flag instance variables into methods as they require a renderer configuration to be generated.