add drone CI

.drone.yml

@@ -0,0 +1,34 @@
+---
+kind: pipeline
+type: docker
+name: default
+
+steps:
+  - name: build
+    image: python:2.7
+    environment:
+      PLATFORMIO_CI_SRC: "src"
+    commands:
+      - pip install -U platformio
+      - platformio run
+      - platformio ci --lib="script" --project-conf platformio.ini --board=lolin_d32_pro --build-dir="build" --keep-build-dir
+
+  - name: gitea_release
+    image: plugins/gitea-release
+    settings:
+      api_key:
+        from_secret: gitea_token
+      base_url: https://dev.xd0.de
+      files: dist/*
+    when:
+      event: tag
+
+  - name: notify
+    image: drillster/drone-email
+    settings:
+      host: mail.xd0.de
+      from: drone@xd0.de
+      recipients:
+        - hendrik+dev@xd0.de
+    when:
+      status: [ changed, failure ]

README.md

@@ -2,6 +2,8 @@
 
 Wetterstation v2 with ESP32 and various sensors
 
+[![Build Status](https://drone.xd0.de/api/badges/hendrik/esp32-weatherstation/status.svg)](https://drone.xd0.de/hendrik/esp32-weatherstation)
+
 ## Hardware
 * ESP32 µC