Bux fixes

• the call to logging.basicConfig() in pool.py has been dropped: it was messing with some projects using logging (and a library should not initialize the logging system anyway.)
• psycopg now correctly handles time zones with seconds in the UTC offset. The old register_tstz_w_secs() function is deprecated and will raise a warning if called.
• Exceptions raised by the column iterator are propagated.
• Exceptions raised by executemany() iterators are propagated.