TAJO-920: Add FIRST_VALUE and LAST_VALUE window functions. (Keuntae Park via hyunsik)

Closes #308
Merge branch 'master' into HYNIX-SELECT
TAJO-1272: Change snapshot version from 0.9.1 to 0.10.

Closes #323
TAJO-269: Protocol buffer De/Serialization for LogicalNode.

Closes #322
TAJO-1176: Implements queryable virtual tables for catalog information

Closes #273
added a missing commit log to CHANGES
Merge branch 'master' into HYNIX-SELECT
modify test case and result for duplicated column test
Merge branch 'HYNIX-SELECT' of https://github.com/sirpkt/tajo into HYNIX-SELECT