journal: add minimal journal gateway daemon based on GNU libmicrohttpd

This minimal HTTP server can serve journal data via HTTP. Its primary
purpose is synchronization of journal data across the network. It serves
journal data in three formats:

       text/plain: the text format known from /var/log/messages
       application/json: the journal entries formatted as JSON
       application/vnd.fdo.journal: the binary export format of the journal

The HTTP server also serves a small HTML5 app that makes use of the JSON
serialization to present the journal data to the user.

Examples:

This downloads the journal in text format:

 # systemctl start systemd-journal-gatewayd.service
 # wget http://localhost:19531/entries

Same for JSON:

 # curl -H"Accept: application/json" http://localhost:19531/entries

Access via web browser:

 $ firefox http://localhost:19531/

1 files changed, 15 insertions, 0 deletions

diff --git a/units/systemd-journal-gatewayd.socket b/units/systemd-journal-gatewayd.socket
new file mode 100644
index 0000000000..fd11058ab4
--- /dev/null
+++ b/units/systemd-journal-gatewayd.socket
@@ -0,0 +1,15 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Journal Gateway Service Socket
+
+[Socket]
+ListenStream=19531
+
+[Install]
+WantedBy=sockets.target