enable user updates

`POST`ing to /user/<user> with json will update profile.
clean up
remove log line
add api section for re-usable bits, refactor users

Basically works.
remove dead code
record WIP: server.fetchUser, server.updateUser

switch everything to use server.fetchUser and server.updateUser.
Seems to work :-).
remove dead code
make update/create/fetch user work more reliably
record WIP, moving helpers around
clean up/re-organize user helpers

Convert everything to using shared helpers.
eliminate crufty default-fetch

The default- prefix felt crufty.  Now that everything is in a small
module, the registration logic fits in one place.  As a benefit, it's
now easy to view all expected inputs and outputs in one page.
test most of events
quick test of users api
simplify update name test
cover ~89% of user api stuff
make clean test
WIP tests: stuck on upload testing
test upload and download
add tests
explicitly clean between runs