Allow to define the namespace/package separator

[akkie]

PHP as example uses a back slash as its namespace separators. But in the BasicGenerator.scala file a dot is hard coded to generate the API bundle and the model map.

It would be nice if the generator would introduce a property which defines this separator, so that it can be overwritten by the language specific generators.

Currently the only working solution is to override the methods prepareModelMap and prepareApiBundle.

[fehguy]

@akkie is this still an issue?