Add docker image build testing

.drone.yml

@@ -4,6 +4,14 @@ kind: pipeline
 name: default
 
 steps:
+  - name: Build Homebase docker image
+    image: docker:stable
+    volumes:
+      - name: docker_sock
+        path: /var/run/docker.sock
+    commands:
+      - docker build --no-cache -t autonomic/homebase:drone .
+
   - name: Deploy Homebase with Dokku
     image: appleboy/drone-git-push:0.2.0-linux-amd64
     settings: