loading notebook using tag-name
Merge branch 'develop' into pr/989
improvements to loading notebook by tag

for @amol-jore
do version_by_tag in the same place as notebook_by_name
version_of_tag -> version_by_tag follow precedent

various bugfixes
update url when changing tag of current notebook
fixed bug where it wasn't editable right after it was edited
make sure recreated notebook version tree nodes are editable
null an empty tag before updating in rcloud
fix bug where make_editable didn't work inside on_create_tree_li