Make user app form vertical instead of horizontal

This should allow even really LONG email addresses to fit nicely in the user list view.
Ensure updates won't wipe out existing fields

This solves the problem of passwords getting clobbered in the
users table. I've tested it, and inserts are unaffected, with one
minor difference: the order in which the fields are stored seems
to vary depending on whether $set is used or not. (At least, the
order in which the fields will be printed by the mongo command
line interface certainly depends on whether $set is used.) But
since field order doesn't matter one bit, this should not be a
problem.

Bonus: only one line of code needed to change to fix the bug!