URL for exports are incorrect using jupyterhub

[fdion]

I think there is an issue with this function:

hide_code/hide_code/hide_code.js

Line 157 in 3cac3b8

function exportLink(path){

Export links show up as /hub/notebooks/... instead of /user/userid/notebooks/... and thus a 404.

[kirbs-]

Thanks for reporting.