use confd from repo

Dockerfile

@@ -1,21 +1,6 @@
 FROM quay.io/thallian/alpine-s6
 
-ENV VERSION=v0.12.0-alpha3
+RUN apk add --no-cache --repository http://dl-3.alpinelinux.org/alpine/edge/testing/ --allow-untrusted confd 
-
-RUN apk add --no-cache go gcc musl-dev libressl tar git
-
-RUN mkdir -p /src/confd
-RUN wget -qO- https://github.com/kelseyhightower/confd/archive/$VERSION.tar.gz | tar -xz -C /src/confd --strip 1
-
-WORKDIR /src/confd
-ENV GOPATH /src/confd/vendor:/src/confd
-RUN go get -d
-RUN go build -a -installsuffix cgo -x .
-RUN mv ./confd /bin/
-RUN chmod +x /bin/confd
-
-RUN apk del go gcc musl-dev libressl tar git
-RUN rm -rf /src
 
 WORKDIR /