Allow access/edit of private pathways by login

[khanspers]

Right now it is impossible to open a pathway that is set to private at WP, even for the original author. The search feature will find the pathway, but when trying to open it a message appears saying "The pathway is not found".

1 It should be possible for the original author, and other users who are allowed access at WP, to open /edit/update the pathway, by entering their login info.

1. The message that is displayed for users who don't have access should be changed to something more informative, like "You don't have permissions to view/edit this pathway"