Fix 'show records' options lookup & more feedback

Hi Julien!

Fixed couple of new issues.
* Use correct key to lookup options for 'show table'.
* Give some feedback to user when running SQL commands.
* PostgreSQL: use generic function to determine default schema (usually 'public'). When ordering tables in the list, show the tables from default schema first.
* PostgreSQL: Remove bad options for 'show table' command. Probably it was copied from MySQL config.

Nice plugin!