Sessions can't accept "/" in name

I would like to name my sessions by my work's git branch naming convention, which is `[ticket-number]/[description]`, but startify interprets a "/" as if it's a path so when I do this it saves fine but it doesn't list in the startify screen.

Start by reproducing the issue in the Startify screen with a session name containing "/", then trace how session names are saved and listed. Done means names using the reported git-branch convention are saved and appear in the Startify screen without being treated as paths.

Written by the indexing model from the issue text.