feat: implement and test tailer file component

vendor/go.uber.org/zap/checklicense.sh

@@ -0,0 +1,17 @@
+#!/bin/bash -e
+
+ERROR_COUNT=0
+while read -r file
+do
+	case "$(head -1 "${file}")" in
+		*"Copyright (c) "*" Uber Technologies, Inc.")
+			# everything's cool
+			;;
+		*)
+			echo "$file is missing license header."
+			(( ERROR_COUNT++ ))
+			;;
+	esac
+done < <(git ls-files "*\.go")
+
+exit $ERROR_COUNT