Support 'qs' media type parameters

Media type 'qs' parameters can affect the selection algorithm choosing the best method candidate and the response media type, for example, given

Accept: application/xml, application/json

and

@Produces("application/xml;qs=0.8, application/json")
public Response a() {}

the response media type is "application/json", where as with

@Produces("application/json;qs=0.8")
public Response a() {}

@Produces("application/xml;qs=0.9")
public Response b() {}

b() gets selected and the response media type is 'application/xml'