Getting Rancher plugin to conform to the current drone-plugins conventions

Dockerfile

@@ -1,11 +1,16 @@
-# Docker image for the Drone build runner
-#
-#     CGO_ENABLED=0 go build -a -tags netgo
-#     docker build --rm=true -t plugins/drone-rancher .
+FROM alpine:3.6 as alpine
+RUN apk add -U --no-cache ca-certificates
 
-FROM gliderlabs/alpine:3.2
-RUN apk add --update \
-  ca-certificates
-ADD drone-rancher /bin/
+FROM scratch
+
+ENV GODEBUG=netdns=go
+
+COPY --from=alpine /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+
+LABEL org.label-schema.version=latest
+LABEL org.label-schema.vcs-url="https://github.com/josmo/drone-rancher.git"
+LABEL org.label-schema.name="Drone Rancher"
+LABEL org.label-schema.vendor="Josmo"
+
+ADD release/linux/amd64/drone-rancher /bin/
 ENTRYPOINT ["/bin/drone-rancher"]
-