Add pygments to IPython dependencies

This is needed for running "ipython nbconvert".
Add sphinx to IPython run-time dependencies

This is needed for nbconvert to latex.
Update Sphinx to 1.2b3
Sphinx: don't use an egg
Merge pull request #78 from certik/ipython2

Add pygments to IPython dependencies
Add ipywidgets
Add dftatom
dftatom: Fix the rpath issue