This allows future App versions to also work with the invite page
without having to screen scrape the content.
Fixes#56 (at least for the portal side of things).
Tester feedback has shown that desktop client users will also
click that button because they are, in fact, not on mobile.
This button speaks more to the users intent (sending the
invitation to the mobile device) after having (hopefully) read
the text above.
Fixes#38.