v0.3.1: imporve error message in case of calling unknown functions

v0.3.0: add python support, imporve VirtualModule#new API, add more e…

…xamples including doc2vec etc

v0.2.1: improve VirtualModule#new API design, refactor in preparation…

… for adding jruby/python support

fix typo

Merge pull request #1 from PallHaraldsson/patch-1

Typo