test: Add a new local end-to-end test

This patch introduces a new directory, test/, which contains a simple local
end-to-end test which runs a chasquid binary and uses msmtp to send an email,
which is delivered locally.

As it's the first one, it adds a bunch of common infrastructure to simplify
writing these kinds of tests.

More end-to-end tests will follow, and it's expected that the common
infrastructure will also change significantly to accomodate their needs.

test/t-simple_local/run.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -e
+. $(dirname ${0})/../util/lib.sh
+
+init
+
+generate_certs_for testserver
+
+chasquid -v=2 --log_dir=.logs --config_dir=config &
+wait_until_ready 1025
+
+run_msmtp someone@testserver < content
+
+wait_for_file .mail/someone@testserver
+
+mail_diff content .mail/someone@testserver
+
+if run_msmtp -a baduser someone@testserver < content 2> /dev/null; then
+	echo "ERROR: successfully sent an email with a bad password"
+	exit 1
+fi
+
+if run_msmtp -a badpasswd someone@testserver < content 2> /dev/null; then
+	echo "ERROR: successfully sent an email with a bad password"
+	exit 1
+fi
+
+success