Adds HTML title elements to templates that extend either `base.html`,
`portico.html` or `portico_signup.html`, and that are not website
portico landing pages that will use the `PAGE_TITLE` variable to set
the HTML title element (see following commit in series).
Also, updates some templates for missing translation tags.
As a general rule, we want the title element (and page content)
translated. Exceptions that are updated in this commit are templates
used in the development environment, analytics templates that are used
by staff and templates related to Zephyr.
This both is better copy and also cleared for translators, who in
languages with gendered nouns don't need to guess what gender to use
for "one" without context.
This completes the last commit's work to fix CVE-2017-0910, applying
to any invite links already created before the fix was deployed. With
this change, all new-user registrations must match an explicit realm
in the PreregistrationUser row, except when creating a new realm.
[greg: rewrote commit message]
Alex Vandiver
Lauryn Menard
Khushiyant
Tim Abbott
Vishnu KS
Utkarsh Patil
Vishnu Ks