Link in sharing email doesn't work when not logged-in

[baranan]

• I got an email notifying me that another user shared a study with me
• I clicked the link to become a collaborator
• I wasn't logged in so I had to login
• The study was not added to my Studies list
• Click the link again (now that I'm logged in), and this time the study was added to my studies list.

It is fine to require the login, but you should then redirect to the url that activates the action I request (e.g., approve collaboration).

[ronenno1]

Done.