- added unit test for exception formatting

- added unit test for exception formatting
- Deprecated the hardcoded TIMESTAMP function, which when
used as func.TIMESTAMP(value) would render "TIMESTAMP value".
This breaks on some platforms as Postgres doesn't allow
bind parameters to be used in this context.  The hard-coded
uppercase is also inappropriate and there's lots of other
PG casts that we'd need to support.  So instead, use
text constructs i.e. select(["timestamp '12/05/09'"]).