Update .travis.yml

.travis.yml

 language: java
 jdk:
+  - oraclejdk7
   - oraclejdk8
+  
 before_install:
   - pip install --user codecov
+
 after_success:
   - mvn clean cobertura:cobertura coveralls:report
+  - mvn clean site -X
   - codecov
+
 branches:
   only:
     - master