TAJO-1109: Separate SQL Statements from Catalog Stores

This is a re-created pull request for this request, https://github.com/apache/tajo/pull/201.
I think that difference on upgrade approach might come with who will perform upgrade processes on Tajo. My approach considers software engineers who do not know about RDBMS or do not have the privileges on RDBMS. However, with your approach, it is needed to engage database administrator when upgrading catalog information. Both approaches have pros and cons, but if catalog schema has changed rapidly, your approach may be suitable. My approach will be difficult to maintain the catalog schema if these changes occur frequently.
I will restore source codes on version check, and will commit soon.