Save article metadata* in a picke in WikiCorpus
Save doc id to metadata dictioanry in serializer
Add metadata argument to all save_corpus functions
Check if corpus has metadata attribute before trying to use it
Add CBOW
Add newline at end of word2vec_inner.pyx
'sg' now the last formal parameter of __init__()

Allows people initializing Word2Vec models using positional arguments to
keep the same syntax
Use the wrapped pickle in utils.
Merge branch 'develop' into p_develop
Merge pull request #169 from josephcc/develop

Create a dictionary that maps document id to some metadata of the original corpus
Add unit test (for CBOW)
update CHANGELOG
Merge branch 'develop' of github.com:piskvorky/gensim into develop
Merge pull request #176 from sebastien-j/cbow

CBOW
Merge branch 'develop' of github.com:piskvorky/gensim into develop
credit CBOW word2vec + pep8 fixes re. #176
CHANGELOG credit for Joseph's metadata API