.travis.yml: remove oraclejdk7 (no longer available) and add openjdk6

(side-effects: close apache#1, close apache#4)

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/codec/trunk@1803412 13f79535-47bb-0310-9956-ffa450edef68

Author: PascalSchumacher

.travis.yml

@@ -17,8 +17,8 @@ language: java
 sudo: false
 
 jdk:
+  - openjdk6
   - openjdk7
-  - oraclejdk7
   - oraclejdk8
 
 after_success: