This sends an event when a new avatar is uploaded that refreshes the
avatar for all browser clients without the need to reload the browser.
Fixes: #1359.
Previously, we were checking if a particular user was the current user
in dozens of places in the codebase, and correct case-insensitive
checks were not used consistently, leading to bugs like #502.
Since it's basically impossible to add a person with an
undefined full_name--even "skeleton" people--there is no
need to check the full_name field to short circuit reify(),
because it will always be defined.
(imported from commit 3a30cfd583a040f7460739abea1604594c450ffe)