Summary
Using ./platform -invite_user -team_name="team" -email="email" sends an email with an invalid link.
Steps to reproduce
Just run ./platform -invite_user -team_name="team" -email="email"
Expected behavior
The Join Team link in the invite email should take you to the mattermost site URL.
Observed behavior
The link doesn't have the site URL pre-pended It just starts with "/signup_user_complete/" instead of "mattermost.example.com/signup_user_complete".