Add upstart script to run uHub as a service.

Start and stop conditions are based off the OpenSSH upstart script which
ships with Ubuntu.

doc/upstart/etc/init/uhub.conf

@@ -0,0 +1,28 @@
+# uHub - a lightweight but high-performance hub for the ADC
+#        peer-to-peer protocol.
+
+description "uHub - High performance ADC peer-to-peer hub"
+
+# Start and stop conditions.
+start on filesystem or runlevel [2345]
+stop on runlevel [!2345]
+
+# Allow the service to respawn, but if its happening too often
+# (10 times in 5 seconds) theres a problem and we should stop trying.
+respawn
+respawn limit 10 5
+
+# The program is going to fork, and upstart needs to know this
+# so it can track the change in PID.
+expect fork
+
+# Set the mode the process should create files in.
+umask 022
+
+# Make sure the log folder exists.
+pre-start script
+    mkdir -p -m0755 /var/log/uhub
+end script
+
+# Command to run it.
+exec /usr/bin/uhub -f -u uhub -g uhub -l /var/log/uhub/uhub.log -c /etc/uhub/uhub.conf