[#54154720] expand account details, and add account edit (nickname only
for now)
make nickname sparse, so we can create account without one, but once
it's set, it must be unique
nickname shouldn't default to "" and should validate if val == null, now
that it's sparsely indexed
gravatar should show default icon if user doesn't have a gravatar
account
if user doesn't have a nickname, show their ownership using their email
address
show accounts by id, not nickname or email. if we use nickname, what
about people without nicknames? if we use email, we're exposing emails
of people who might have nicknames.
in spime details, show email for owner if nickname is not available