Update docker build to 0.1.2 (#793)

* build: use 0.1.2 for docker build

* feat: tag latest when tagging new docker release

docker/Release.dockerfile

@@ -1,6 +1,6 @@
 FROM docker.mirror.hashicorp.services/alpine:3.10
 
-ARG VERSION=0.1.1
+ARG VERSION=0.1.2
 
 LABEL name="Boundary" \
       maintainer="HashiCorp Boundary Team <boundary@hashicorp.com>" \