- issue2551223 - fix timestamp truncation in mysql and postgresql The data types used to represent timestamps in pg and mysql for ephemeral tables: sessions and otks don't have enough signifcant digits to work. As a result the timestamps are rounduped (up/down) rsuling in the stored timestamp being 2 minutes (pg) or 2-3 hours(mysql) off from what it should be. Modify db schema to use a numeric type that preserves more significant figures. Implement schema upgrade. Document need for upgrade in upgrading.txt. Write tests for schema upgrade. Implement test for updateTimestamp method on BasicDatabase that showed this issue in the first place. Write overrides for test for anydbm/memorydb which store timestamp properly or not at all.

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