Prepare for v0.3.0 and add migration path from v0.2.1.x

make_docker.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+BIN=target/release/garage
+DOCKER=lxpz/garage_amd64
+
+TAG=$1
+if [ -z "$1" ]; then
+	echo "Usage: $0 <tag>"
+	exit 1
+fi
+
+RUSTFLAGS="-C link-arg=-fuse-ld=lld -C target-cpu=x86-64 -C target-feature=+sse2" cargo build --release --no-default-features
+cp $BIN $BIN.stripped
+strip $BIN.stripped
+
+docker pull archlinux:latest
+docker build -t $DOCKER:$TAG .
+docker push $DOCKER:$TAG
+docker tag $DOCKER:$TAG $DOCKER:latest
+docker push $DOCKER:latest