TajoDump cannot dump upper/lower mixed case database names.

When users use upper/lower mixed case database names, TajoDump does not work correctly. This patch fixes this bug. In addition, this patch adds the unit test for TajoDump.

Additionally, this patch fixes some trivial column resolving bug caused when a column name in target list is not fully qualified and another database different from the current database of the session is used in FROM clause.

Example:

SELECT "LineItem".L_ORDERKEY FROM "TestSelectQuery"."LineItem";