Update JVM to 8u191 on jenkins workers

the jvm we're using to build/test spark on the centos workers is a bit...  long in the teeth:

[sknapp@amp-jenkins-worker-04 ~]$ java -version
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

on the ubuntu nodes, it's only a little bit less old:

sknapp@amp-jenkins-staging-worker-01:~$ java -version
java version "1.8.0_171"
Java(TM) SE Runtime Environment (build 1.8.0_171-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b11, mixed mode)

steps to update on centos:

• manually install new(er) java
• update /etc/alternatives
• update JJB configs and update JAVA_HOME/JAVA_BIN

steps to update on ubuntu:

• update ansible to install newer java
• deploy ansible

questions:

• do we stick w/java8 for now?
• which version is sufficient?

srowen