more persistence

[Colin Walters <walters redhat com>]

Hey,

I just tracked down some bugs I introduced with persistence that broke
comment closing; having persistence means we need to be careful about
the lifecycle of objects with respect to the Hibernate session.

In particular I was storing Person objects in the LiveComment (one
Hibernate session) and passing them to the constructor of the
ClosedComment (a 2nd session).

There are possibly other issues like this; be on the lookout.