Add Drone configuration.

.drone.yml

@@ -0,0 +1,15 @@
+---
+kind: pipeline
+type: docker
+name: build
+
+steps:
+  - name: docker
+    image: plugins/docker
+    settings:
+      username:
+        from_secret: dockerhub_user
+      password:
+        from_secret: dockerhub_password
+      repo: pztrn/npf
+      auto_tag: true