feat: add dep-dl

* https://github.com/take-cheeze/dep-dl
* golang/dep#289 (comment)

Author: suzuki-shunsuke

Dockerfile

@@ -3,6 +3,7 @@
 # gometalinter
 # bash
 # dep
+# dep-dl https://github.com/take-cheeze/dep-dl
 # golang
 FROM node:8.11.3-stretch AS build-env
 FROM golang:1.10.3
@@ -20,4 +21,5 @@ RUN go get -u gopkg.in/alecthomas/gometalinter.v2 && \
     tar xvzf ghr_${GHR_VERSION}_linux_amd64.tar.gz && \
     mv ghr_${GHR_VERSION}_linux_amd64/ghr /usr/local/bin && \
     rm -R ghr_${GHR_VERSION}_linux_amd64 && \
-    go get github.com/mitchellh/gox
+    go get github.com/mitchellh/gox && \
+    go get -u github.com/take-cheeze/dep-dl

README.md

@@ -7,6 +7,7 @@ https://hub.docker.com/r/suzukishunsuke/go-ci/
 * Debian Stretch
 * Golang 1.10.3
 * [dep](https://github.com/golang/dep)
+* [dep-dl](https://github.com/take-cheeze/dep-dl) https://github.com/golang/dep/issues/289#issuecomment-385968184
 * [gometalinter](https://github.com/alecthomas/gometalinter)
 * [ghr v0.10.2](https://github.com/tcnksm/ghr)
 * [gox](https://github.com/mitchellh/gox)