Add license terms file

This adds a stripped version of the IPython license file.
Update README

Clarify IPython-contrib status
Update README

Clayrify IPython-contrib relationship to IPython
Merge pull request #76 from juhasch/copyright

Add license terms file
Update copyright notice

Remove IPython Development Team copyright notice
Merge pull request #78 from juhasch/copyright

Update copyright notice
Merge remote-tracking branch 'upstream/master'
Merge pull request #77 from jcjaskula/executeTimings

Show when and how long a cell has been executed
Merge remote-tracking branch 'upstream/master'
Update aspell extension

- use require to load CSS
- load CSS from /nbextensions now
Merge pull request #80 from juhasch/aspell

Update aspell CSS loading
Merge pull request #81 from jcjaskula/executeTimings

Added images for the wiki page
Merge remote-tracking branch 'upstream/master'