The message should be seen on Join Wiki page when you invite users to join a wiki

Steps to reproduce:
1. Create a new wiki
2. After installation go to the new Wiki Administration Page -> Users & Groups and click on Users.
3. Below "Add or invite users to wiki" search for a user, write a message and press Invite.
4. Login with a normal user.
5. Hover over Home and click on "Wiki Index"
6. Click on the "View Invitation" link
7. Notice that the Message sent is not visible on this page.

A user should see the message on Join Wiki page and not to go on Activity Stream to check it.

See the attached pictures.