Update custom.js example

- Use IPython.load_extensions
- Assume all extensions reside in `nbextensions`
Update runtools

- use new icon naming scheme
- update to require.js
Update navigation-hotekys extension

- fix ctrl+y
- change shift/ctrl-enter behavior to just go into edit mode after
execution
Make custom.example.js run in IPython 2
Update custom.example.js
Use app_initialized.NotebookApp
Sync to ipython-contrib
Update printview_button to 3.x

- use notebook_patch
- new icon name
Merge pull request #101 from juhasch/printview

Update Printview_button to 3.x