remove non lts oracle java versions

oracle java11 not yet supported by travis it seems 
close #2227

Author: duncdrum

.travis.yml

@@ -5,10 +5,9 @@ matrix:
     - jdk: openjdk8
     - jdk: oraclejdk8
     - jdk: openjdk9
-    - jdk: oraclejdk9
     - jdk: openjdk10
-    - jdk: oraclejdk10
     - jdk: openjdk11
+#     - jdk: oraclejdk11
     - os: osx
       osx_image: xcode9.2
       env: JAVA_HOME=$(/usr/libexec/java_home)