Log Message:
py-notebook: updated to 5.4.1

5.4.1
A security release to fix CVE-2018-8768.

5.4.0
Fix creating files and folders after navigating directories in the dashboard
Enable printing notebooks in colour, removing the CSS that made everything black \ 
and white
Limit the completion options displayed in the notebook to 1000, to avoid \ 
performance issues with very long lists
Accessibility improvements in tree.html
Added alt-text to the kernel logo image in the notebook UI
Added a test on Travis CI to flag if symlinks are accidentally introduced in the \ 
future. This should prevent the issue that necessitated :ref:release-5.3.1
Use lowercase letters for random IDs generated in our Javascript
Removed duplicate code setting TextCell.notebook