Including importnb into ipynb

[tonyfast]

addresses #45 starts to include the importnb machinery in the ipynb repo.

importnb has features that address a few open issues #38 #6 #44

• In the short term should we include both ipynb and importnb in the namespace?
• Should we change importnb to ipynb or retain importnb?

[yuvipanda]

woohoo, awesome.

I think what we should do is:

1. Emit warnings from ipynb about pending changes, and make a point release
2. Emit warnings from importnb about pending move, and make a point release there.
3. Move importnb into the ipynb namespace. Write docs on how people can switch. Make a major release.
4. Write a blog post.

How does that sound?

[yuvipanda]

@Carreau I don't have admin access to this repo, can you add @tonyfast and @bollwyvl to this repo?