Release 0.4

[EmpireErwinKooi]

Please create a release 0.4 so the latest released code matches the documentation in readme.md.
Eg when I pip install schemapi now, the documentation does not reflect what gets installed.

[pletnes]

Seconded, I tried running this snippet, but the class SchemaModuleGenerator just does not exist:

>>> import schemapi
>>> api = schemapi.SchemaModuleGenerator(schema, root_name='Person')

I might be able to contribute if you'd give me some hints on what work is required. I would like to use an official PyPI release rather than a git-clone-installation.

[camillescott]

Any news? I'd like to use schemapi in a project, but as it stands I'd need to vendor it. Appreciate your efforts!