infra: buildbot master configs and slave systemd service file

* master: master.cfg and example pass.cfg file
* worker: systemd service unit file.

  Setting up a slave/worker is trivial:

  su - buildbot
  buildslave create-slave . radia.quagga.net buildbot-<name> <password>
diff --git a/infra/buildbot/master/pass.cfg b/infra/buildbot/master/pass.cfg
new file mode 100644
index 0000000..34a9340
--- /dev/null
+++ b/infra/buildbot/master/pass.cfg
@@ -0,0 +1,21 @@
+# -*- python -*-
+# ex: set syntax=python:
+
+# example pass.cfg
+
+# privileged users for webui and try building
+#users = [
+#    ('foo', 'password123'),
+#]
+
+workers_pass = {
+          "fedora-24":  "aaaaaaa",
+          "centos-7":   "bbbbbbb",
+          "debian-8":   "ccccccc",
+          "debian-9":   "ddddddd",
+          "freebsd-10": "eeeeeee", 
+          "freebsd-11": "fffffff",
+}
+
+#### debug
+#debugPassword = "abcdefghijklmnopqrstuvwxyz"