Add initial gitlab ci file

.gitlab-ci.yml

+image: maven:latest
+
+variables:
+  PORT: "5000"
+
+build:
+  stage: build
+  script:
+    - mvn compile
+
+test:
+  stage: test
+  script:
+    - mvn test
+
+deploy:
+  stage: deploy
+  script:
+    - mvn package
+    - sh target/bin/simplewebapp
+  only:
+    - master