Make User::newFromName set the user object's ID attribute, so it can

Make User::newFromName set the user object's ID attribute, so it can
be used for other methods and lazy loading. Previously, you had to use
the class method idForName and assign its value using setId(). Since
all the code that was using newFromName was doing this, it seems like
client programs want a "real" User returned from newFromName. Replaced
client code that was doing newFromName, idForName, setId with just
newFromName. This doesn't seem to break newFromName's semantics; it
seems intuitive (to me) that the user object returned from newFromName
should be usable as returned.