ENG-4668: Fix latency stats.  Add test case to TestStatisticsSuite
ENG-4645: DRIVE-BY!  Add a missing length check to the stats returned
by the EE for tables, to match the sane check for indexes.  Add a test
case demonstrating successful database start with an empty schema.
Merge pull request #504 from VoltDB/eng4668

Eng4668, r=aweisberg for the first commit, not worried about the second