TAJO-353 (database support), some bugs are also introduced to code.
This patch fixes the bugs as follows:
- \d "ABC" does not work.
- tajo_dump cannot handle some identifiers to be double quoted.
- the same table names in different databases are not allowed.
In this patch, I fixed all bugs that I found, and added some unit tests to reproduce the cases.
This is a critical issue. So, I'd like to ask the quick review.