Add Travis-CI yml (#39)

* Add Travis-CI yml.

* Add some whitespace.

* Run integration tests without maven-gpg-plugin.

* Skip the install step.

Author: cstroe

.travis.yml

@@ -0,0 +1,15 @@
+language: java
+
+sudo: false
+
+jdk:
+  - oraclejdk8
+
+cache:
+  directories:
+    - $HOME/.m2
+
+# skip mvn install
+install: true
+
+script: mvn clean package invoker:install invoker:run