Revert "build: Downgrade to Java 1.7"

This reverts commit bc30e65ea2d14d71fabca92c96aef089f4b77d43.

Change-Id: If6bcd1218c6d0e3753af7ad351fba4784b5ac6ad
diff --git a/.travis.yml b/.travis.yml
index e358d25..9bcf999 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,3 @@
 language: java
 jdk:
-  - oraclejdk7
+  - oraclejdk8