DBCP-505: Update Java requirement from version 7 to 8.

Travis CI: Remove Java 7
diff --git a/.travis.yml b/.travis.yml
index a626b6d..3961ad0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,5 +17,4 @@
 sudo: false
 
 jdk:
-  - openjdk7
   - oraclejdk8
\ No newline at end of file