Refactor Dockerfile

Dockerfile

@@ -1,6 +1,13 @@
 FROM		znly/protoc
-RUN apk --update add make git go rsync
+
+ENV		GOPATH=/go \
+		PATH=/go/bin:${PATH}
+
+# Install deps and common tools
+RUN		apk --update add make git go rsync libc-dev \
+ &&		go get -u golang.org/x/tools/cmd/goimports
+
+# Install protoc-gen-gotemplate
 COPY		.	/go/src/github.com/moul/protoc-gen-gotemplate
 WORKDIR		/go/src/github.com/moul/protoc-gen-gotemplate
 RUN		go install .
-ENV PATH=${PATH}:${GOPATH}/bin