TAJO-1018: Separate algebraic representation from LogicalNode

https://dbserver.korea.ac.kr/jira/browse/TAJO-1018
TAJO-1019: Implement SQL2003 parser and its analyzer to output algebraic representation

https://dbserver.korea.ac.kr/jira/browse/TAJO-1019
Merge pull request #107 from hyunsik/TAJO-1019

Separate algebraic representation from LogicalNode and Implement a SQL2003 parser to support it