Add drone config.

.drone.yml

@@ -0,0 +1,50 @@
+---
+kind: pipeline
+type: docker
+name: default
+
+platform:
+  os: linux
+  arch: amd64
+
+workspace:
+  base: /src
+
+steps:
+- name: build
+  pull: if-not-exists
+  image: leophys/signal-builder:0.1
+  commands:
+  - sed -i"" 's/inputFile\.delete()//' /src/app/build.gradle
+  - /src/gradlew assembleRelease || true
+  - /src/sign.sh
+  environment:
+    KEY_PASSWORD:
+      from_secret: key_password
+    KEY_PATH: /secrets/key.jks
+  volumes:
+  - name: builds_output
+    path: /builds/
+  - name: secrets
+    path: /secrets
+
+volumes:
+- name: builds_output
+  host:
+    path: /var/builds/signal
+- name: secrets
+  host:
+    path: /var/drone/secrets
+
+trigger:
+  branch:
+  - master
+  event:
+  - push
+  - cron
+
+---
+kind: signature
+hmac: 1f36630119748326d827330cb73300fd9a858ff238461c0258d77ecdda182e0b
+
+...