Increase compatibility with postgres time type.

Allow for miliseconds in 24h format, but discard them.

Allow 24:00:00 for time value, as this is a valid value for PostgreSQL. As it
would be hard to allow value of 24:00:00 internally, this is
casted as 23:59:59

More information:
http://www.postgresql.org/docs/9.3/static/datatype-datetime.html