added travis CI

.travis.yml

@@ -0,0 +1,17 @@
+before_install:
+ - chmod +x gradlew
+ - |
+   if ! git diff --name-only $TRAVIS_COMMIT_RANGE | grep -qvE '(.md)|^(LICENSE)'
+   then
+     echo "Not running CI since only docs were changed."
+     exit
+   fi
+
+install: ./gradlew assemble
+
+script: ./gradlew clean build --info
+
+language: java
+
+jdk:
+  - oraclejdk11