Upgrade to postgresql-async 0.2.10, type changes

This involved two significant changes to basic types:

dbrary.Timestamp changed from DateTime to LocalDateTime, since the
database was already using timestamp without timezone.  Rather than try
to determine the appropriate local timezone for each timestamp, or add
timezone everywhere, it seemed simpler to simpler use UTC times
everywhere.  dbrary sets joda's default timezone appropriately.  This
also requires a postgresql server configuration change for it to use UTC
as well.  I have not attempted to fix old timestamps with an evolution
as there are just too many of them, and being a few hours off doesn't
seem disastrous at this point.

dbrary.Offset changed from seconds : Double to millis : Long in order to
accommodate the new Period parser for interval types.  This meant
changes to many places that did offset calculations.  It also imposes a
millisecond-resolution limit on all offset-related operations (include
frame grabbing and slots).  In fact, this limitation existed some places
already, and where it didn't it often created problems with round-off
errors.  A brief check on the current database indicates that all slot
segments are already millisecond-aligned (for some reason).  More
testing should be done to ensure that slots are recoverable.  I did not
create a date_trunc for segments that could be used to enforce this,
though it may turn out to be necessary.