Changed .travis.yml script to attempt gradle build.

.travis.yml

@@ -1,14 +1,15 @@
-sudo: required
-dist: trusty
-addons:
-  apt:
-    packages:
-      - wget
+language: java
+install: true
+jdk:
+  - openjdk8
 
-before_install:
-  - wget https://github.com/bazelbuild/bazel/releases/download/0.17.1/bazel-0.17.1-installer-linux-x86_64.sh
-  - chmod 755 bazel-0.17.1-installer-linux-x86_64.sh
-  - sudo ./bazel-0.17.1-installer-linux-x86_64.sh
+before_cache:
+  - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -f $HOME/.gradle/caches/*/plugin-resolution/
 
-script:
-  - bazel test --test_output=errors ... |& cat
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+
+script: cd gradle && gradle wrapper && ./gradlew