The nonOverrideable flag is not being processed correctly when it comes to calculating the active set of targets for a promoted reference

There has been much conversation re. the meaning of the nonOverrideable flag that can appear on a component reference. See http://www.mail-archive.com/dev%40tuscany.apache.org/msg16925.html. It seems that we are not applying nonOverrideable when it is set to false and always assume that it is set to true, i.e. we are always aggregating targets down the hierarchy regardless.