add drone

build/ci/.drone.yml

@@ -0,0 +1,18 @@
+kind: pipeline
+type: docker
+name: default
+
+steps:
+  - name: build
+    image: golang
+    commands:
+      - go build -o butler cmd/butler/main.go
+
+  - name: test
+    image: golang
+    commands:
+      - go test ./...
+
+trigger:
+  event:
+    - push