[JDBC] Postgres 10 partitioned tables

The current JDBC driver returns no information about the new partitioned tables in the upcoming Postgres 10.
This is caused by the fact that partitioned tables have a new pg_class.relkind value: 'p'

I have attached a simple patch that fixes the obvious problem that partitioned tables are not returned by getTables()
andno column information is returned from getColumns(). 

The patch essentially treats relkind 'r' and 'p' the same because I think the driver should not make a distinction
betweenregular tables and partitioned tables. 

But I think the bigger is: what do do with the partitions themselves?

Technically they are tables, but I think it would make sense to hide them and let frontend tools deal with displaying
partitionsbelonging to a table (this is e.g. how Oracle does it). 

However, psql displays them as regular tables just like with the "old" inheritance partitions, so that would probably
causesome confusion if getTables() did not return those tables. 


Thomas