add codecov

hack/unit_test.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+set -e
+echo "" > coverage.txt
+
+for d in $(go list ./pkg/... ./cmd/...); do
+  go test -race -coverprofile=profile.out -covermode=atomic $d
+  if [ -f profile.out ]; then
+      cat profile.out >> coverage.txt
+      rm profile.out
+  fi
+done
+
+bash <(curl -s https://codecov.io/bash)