#19 Fix schema qualified tables and \COPY

[Koichi Suzuki]

Nihil's patch to fix the following issue:

Looks like \COPY does not handle schema qualified tables properly. The
COPY command that is sent to the remote nodes forgets to schema
qualify the table:

create schema foo;
create table foo.bar(x int);
\copy foo.bar (x) FROM 'file.txt' with csv;

The above fails. The fix is to schema-qualify the table before sending
it on the wire. We need to be careful about temp tables though. PFA,
patch against HEAD for the same.

[Koichi Suzuki]