Implement token for the Join online event button on the ticket page

[mariobehling]

1. Add the token for video online join button on menu
2. Show a pop-up message for not logged in users or users without a ticket.

Pop up box:

This is a ticketed only event. To access Wikimania Katowice, you must use the ticket link in your confirmation email.

Lost the email? [Resend the email](link to resend order page/area)

Created an account for Wikimania Katowice before? [Log back in here](login page)