Include ".mit.edu" as part of asa.mit.edu URLs

[kchen]

The membership confirmation e-mail I just got says:

Here is the link to provide to members:
https://asa/membership/confirm/

Visit https://asa/membership/submitted/ to see how many people have already
confirmed.

These should have .mit.edu at the end of the URLs. I assume this is dependent on what URL was used to access the site, as I got a different membership confirmation that says:

Here is the link to provide to members:
https://asa.mit.edu:444/membership/confirm/

Visit https://asa.mit.edu:444/membership/submitted/ to see how many people have already confirmed.

and yet another one that says:

Here is the link to provide to members:
https://asa.mit.edu/membership/confirm/

Visit https://asa.mit.edu/membership/submitted/ to see how many people have already confirmed.

[adehnert]

This probably wants to include some kind of fix/replacement for build_absolute_uri that uses the canonical hostname.