Issue SCRUM#159: add .gitlab-ci to generate the docker image

.gitlab-ci.yml

+variables:
+    IMAGE_URL: 'marula.c3sl.ufpr.br:5000/c3sl/agent-gesac'
+    IMAGE_VERSION: '0.1'
+stages:
+    - build
+    - deploy
+
+build:
+    stage: build
+    script:
+        - docker build -t ${IMAGE_URL}:${IMAGE_VERSION} -t ${IMAGE_URL}:latest src
+    tags:
+        - docker
+        - build
+
+deploy:
+    stage: deploy
+    variables:
+        IMAGE_VERSION: ''
+    script:
+        - docker push ${IMAGE_URL}:${IMAGE_VERSION}
+        - docker push ${IMAGE_URL}:latest
+    tags:
+        - docker
+        - build
+    only:
+        - master
+