add new build scripts & drone ci script

.drone.yml

@@ -0,0 +1,10 @@
+pipeline:
+  build-docker:
+    image: docker:18.06.1-ce
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+    commands:
+      - chmod +x ./build-image.sh
+      - ./build-image.sh
+    when:
+event: [push]

build-image.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+set -e
+set -o xtrace
+
+IMAGE_NAME=warmup_welcome
+
+# clean old images
+OLD_IMAGES=$(docker images $IMAGE_NAME -q --no-trunc)
+if [ -n "${OLD_IMAGES}" ]; then
+  docker rmi -f ${OLD_IMAGES};
+fi
+
+#Build Images
+docker build . -t $IMAGE_NAME