Update list of jdk to test against since travis-ci no longer supports JDK6.

Author: mikesamuel

.travis.yml

@@ -2,10 +2,11 @@ language: java
 sudo: false
 jdk:
  # It's important to test on all these because of a horrible hack in the POM.
- - openjdk6
- - oraclejdk7
+# - openjdk6 # No longer supported by Travis
+ - openjdk7
  - oraclejdk8
- # - oraclejdk9 # Not yet available on travis-ci.com
+# - oraclejdk9 # Not testable on JDK9. Something maybe related to Jacoco mucking with the bootclasspaht
+
 # Additionally pass -Dgpg.skip to suppress signing instead of trying to provision
 # Travis's containers with keys.
 install: mvn install -DskipTests=true -Dmaven.javadoc.skip=true -Dgpg.skip=true -B -V