src/lib/dhcpsrv/mysql_lease_mgr.*
    MySqlLeaseMgr::MySqlLeaseMgr() - now validates schema
    after connecting

    MySqlLeaseMgr::getVersion()  - no longer relies on
    pre-prepared statement or formal statement execution
    error handling

src/lib/dhcpsrv/tests/generic_lease_mgr_unittest.cc
    LeaseMgrDbLostCallbackTest::testDbLostCallback() - replaced
    use of getVersion() with getLease4() for testing DB usability