Fix error on fetching MYSQL_TIME_TYPE fields

Fetching MYSQL_TIME_TYPE family fields except DATETIME fails with;

  *** MYSQL-ERROR: Unsupported type: 10

This commit fix this problem.  This also changes string format for
DATETIME from 'YYYY-MM-DD HH:DD:SS.FFFFFF' to 'YYYY-MM-DD HH:DD:SS'
when FFFFFF, fractional seconds, is zero.  Before MySQL 5.6.4 accept
fractional seconds but don't store them, so it would be useful change
for many cases.