Modified CHANGES.txt to have TEZ-1609 in 0.6
Modified CHANGES.txt to have TEZ-1609 in 0.6

ueshin/apache-tez,apache/tez,jth/tez,Parth-Brahmbhatt/tez,sequenceiq/tez,dongjiaqiang/tez,apache/tez,Parth-Brahmbhatt/tez,bernhardschaefer/tez,guiling/tez,zjffdu/tez,dongjiaqiang/tez,Altiscale/tez,zjffdu/tez,jth/tez,navis/tez,ChetnaChaudhari/tez,Altiscale/tez,guiling/tez,dongjiaqiang/tez,sidseth/tez,amirsojoodi/tez,guiling/tez,Parth-Brahmbhatt/tez,ueshin/apache-tez,navis/tez,sequenceiq/tez,sequenceiq/tez,amirsojoodi/tez,apache/tez,apache/tez,apache/tez,ueshin/apache-tez,Parth-Brahmbhatt/tez,ChetnaChaudhari/tez,sidseth/tez,navis/tez,sidseth/tez,ChetnaChaudhari/tez,zjffdu/tez,amirsojoodi/tez,sidseth/tez,bernhardschaefer/tez,jth/tez,jth/tez,guiling/tez,navis/tez,bernhardschaefer/tez,Altiscale/tez,zjffdu/tez,ueshin/apache-tez,ChetnaChaudhari/tez,bernhardschaefer/tez,amirsojoodi/tez,guiling/tez,Parth-Brahmbhatt/tez,dongjiaqiang/tez,amirsojoodi/tez,dongjiaqiang/tez,zjffdu/tez,Altiscale/tez,ueshin/apache-tez,ChetnaChaudhari/tez,bernhardschaefer/tez,sidseth/tez,navis/tez,jth/tez