add simple drone config

.drone.yml

@@ -0,0 +1,36 @@
+kind: pipeline
+name: deploy
+steps:
+- name: docker 
+  image: plugins/docker
+  settings:
+    username:
+      from_secret: DOCKER_USERNAME
+    password:
+      from_secret: DOCKER_PASSWORD
+    repo: aaronriedel/shbot
+    tags: latest
+  when:
+    branch:
+      include:
+      - master
+    event:
+      include:
+      - push
+- name: docker-build
+  image: plugins/docker
+  settings:
+    username:
+      from_secret: DOCKER_USERNAME
+    password:
+      from_secret: DOCKER_PASSWORD
+    repo: aaronriedel/shbot
+    tags: latest
+    dry_run: true
+  when:
+    branch:
+      exclude:
+      - master
+    event:
+      exclude:
+      - push