Introduced a factory for codegen data containers

This enables users to extend the Codegen* classes
and add their own methods there (which then can
be accessed from the mustache templates)
Introduced a factory for codegen data containers

implementation completed
Make response headers available to the code generator
Merge pull request #340 from martoe/codegenfactory

Introduced a factory for codegen data containers
Merge pull request #341 from martoe/responseheaders

Make response headers available to the code generator
Enable different package names for models

This is done by prefixing the model name with a package string
Failing unittests (Windows) ignored
MCA-specific extension (TODO move to other project)

* template formatting methods
* don't swallow exceptions
* write "x-mca" fields to Codegen classes