Feature/autobuild docker image for each release thru dockerhub auto builds (roboll#886)

* feat: build hook for dockerhub autobuilds

* release new image

* Create pre_build

* Update push

Author: abdennour

hooks/build

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+echo "=> Building container"
+docker build \
+  --tag "$IMAGE_NAME" \
+  --file Dockerfile .

hooks/pre_build

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+go()
+{
+  docker run --rm -v "$(pwd):/workspace" -w /workspace golang:latest go $@;
+}
+
+go get -u github.com/tcnksm/ghr github.com/mitchellh/gox
+go mod vendor

hooks/push

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+echo "=> Fetch unshallow origin"
+git fetch --unshallow origin || true
+
+echo "=> Tag image:"
+docker tag "${IMAGE_NAME}" "${DOCKER_REPO}:$(git describe --tags --abbrev=0 HEAD^)"
+docker tag "${IMAGE_NAME}" "${DOCKER_REPO}:$(git describe --tags --abbrev=0 HEAD)"
+
+echo "=> Push images"
+docker push "${DOCKER_REPO}"