TAJO-1642: CatalogServer need to check meta table first.

[blrunner]

I tested this patch on my laptop. When I tried to start up tajo-0.11.0-SNAPSHOT with the catalog-site.xml file for tajo-0.10.1-SNAPSHOT, TajoMaster printed following messages.

15/06/09 11:38:11 INFO store.MySQLStore: The meta table of CatalogServer already is created.
15/06/09 11:38:11 ERROR store.MySQLStore: Catalog version (2) and current driver version (4) are mismatch to each other
15/06/09 11:38:11 ERROR store.MySQLStore: =========================================================================
15/06/09 11:38:11 ERROR store.MySQLStore: | Catalog Store Migration Is Needed |
15/06/09 11:38:11 ERROR store.MySQLStore: =========================================================================
15/06/09 11:38:11 ERROR store.MySQLStore: | You might downgrade or upgrade Apache Tajo. Downgrading or upgrading |
15/06/09 11:38:11 ERROR store.MySQLStore: | Tajo without migration process is only available in some versions. |
15/06/09 11:38:11 ERROR store.MySQLStore: | In order to learn how to migration Apache Tajo instance, |
15/06/09 11:38:11 ERROR store.MySQLStore: | please refer http://s.apache.org/0_8_migration. |
15/06/09 11:38:11 ERROR store.MySQLStore: =========================================================================

And I found that existing column informations exists normally. For the reference, I succeed to test with only tajo-0.11.0-SNAPSHOT.

[jihoonson]

I think that every database object should be checked.

[jihoonson]

@blrunner thanks for your patch.
I left one comment.

[blrunner]

Hi @jihoonson

Thanks for your review.
I've just updated the patch using your comments.

[jihoonson]

+1 LGTM!