Revert openjdk8 since it's not available on Ubuntu 12 precise

Author: ashawley

.travis.yml

@@ -9,7 +9,7 @@ addons:
   hostname: localhost.local
 
 jdk:
-  - openjdk8
+  - openjdk6
   - oraclejdk8
   - openjdk11
 

admin/README.md

@@ -23,7 +23,8 @@ After these steps, your `.travis.yml` should contain config of the form:
 language: scala
 
 jdk:
-  - openjdk8
+  - openjdk6
+  - oraclejdk8
 
 scala:
   - 2.11.12

admin/build.sh

@@ -17,7 +17,7 @@ set -e
 # Everything after the `#` in the tag name is ignored.
 
 if [[ "$TRAVIS_JDK_VERSION" == "openjdk6" && "$TRAVIS_SCALA_VERSION" =~ 2\.11\..* \
-      || "$TRAVIS_JDK_VERSION" == "openjdk8" && "$TRAVIS_SCALA_VERSION" =~ 2\.1[23]\..* ]]; then
+      || "$TRAVIS_JDK_VERSION" == "oraclejdk8" && "$TRAVIS_SCALA_VERSION" =~ 2\.1[23]\..* ]]; then
   RELEASE_COMBO=true;
 fi