Updated ImpalaDecimalTests to support python2.6
Updated ImpalaDecimalTests to support python2.6

bhtucker/impyla,cloudera/impyla,cloudera/impyla,bhtucker/impyla,mariusvniekerk/impyla,mariusvniekerk/impyla,wesm/impyla,wesm/impyla,laserson/impyla,schaffino/impyla,mariusvniekerk/impyla,laserson/impyla,schaffino/impyla,bhtucker/impyla