TAJO-342: Implement strpos(string, substring) function. (hyoungjunkim via hyunsik)
TAJO-351: TAJO-351: Implement reverse(text). (DaeMyung Kang via hyunsik)
TAJO-349: Implement md5(text). (DaeMyung Kang via hyunsik)
TAJO-346: Implement hex function. (DaeMyung Kang via hyunsik)
TAJO-317: Improve TajoResourceManager to support more elaborate resource management. (Keuntae Park via jihoon)
TAJO-352: Implement right/left(text, size) function. (DaeMyung Kang via hyunsik)