Travis: do not attempt to build 2.7.2 hadoop version on centos 5; declare hadoop versions list for ubuntu 18.04 at the beginning of the script.
Travis: do not attempt to build 2.7.2 hadoop version on centos 5; declare hadoop versions list for ubuntu 18.04 at the beginning of the script.

quantcast/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs