Update Dockerfile to work with latest Caddy

Dockerfile

@@ -1,17 +1,19 @@
-FROM golang:1.11-alpine
+FROM golang:1.12-alpine
 MAINTAINER Peter Teich <peter.teich@gmail.com>
 
 ENV CADDY_VERSION 0.11.1
 
 RUN set -x \
     && apk update && apk add --no-cache --upgrade \
-        openssl git ca-certificates sed bash busybox \
-    && update-ca-certificates \
-    && git clone https://github.com/mholt/caddy.git /go/src/github.com/mholt/caddy \
+        openssl git ca-certificates sed bash busybox
+
+RUN \
+    git clone https://github.com/mholt/caddy.git /go/src/github.com/mholt/caddy \
+    #    && git checkout tags/v${CADDY_VERSION} \
+    && git clone https://github.com/pteich/caddy-tlsconsul.git /go/src/github.com/mholt/caddy/vendor/github.com/pteich/caddy-tlsconsul \
     && cd /go/src/github.com/mholt/caddy \
-    && git checkout tags/v${CADDY_VERSION} \
-    && go get -d github.com/pteich/caddy-tlsconsul \
-    && go get -d github.com/caddyserver/builds
+    && go get -d github.com/caddyserver/builds \
+    && go get -d github.com/hashicorp/consul/api
 
 RUN sed -e "s#// This is where other plugins get plugged in (imported)#_ \"github.com/pteich/caddy-tlsconsul\"#" -i /go/src/github.com/mholt/caddy/caddy/caddymain/run.go