Add build script.

build-arm.sh

@@ -0,0 +1,9 @@
+#!/bin/bash -e
+
+echo "Build binary..."
+GOOS=linux GOARCH=arm go build -v -ldflags="-s -w" .
+
+type upx && {
+    echo "Packing using upx..."
+    upx -9 netatmo-exporter
+} || echo "upx not available"