Clean up a few warts with logging and presentation.

This commit drops our custom ``Object#toString`` mechanisms in favor
of Guava Objects#toStringHelper, which provides a sane and
stylistically consistent manner for doing this same task.  Multiline
emissions are deleted.

A few member fields are shortened to avoid violating style about
verbose names (think Zipf law).

Some of the fragile tests for stringification are deleted.  No sense
in testing something brittle.

Durations have been enhanced to use Joda Time's automatic humanization.

JvmFlagSet now uses an TreeMap<> instead of sorting on every
presentation.  Not that this behavior is performance critical, but might
as well save the work for an immutable type.