Install and start rsyslog. (#2209)

As discussed in #2208, we are using rsyslog for logging, but rsyslog
is not installed on the test server.  This pull request:

- Installs rsyslog on the test server
- Starts it running.

deploy/test-server/install-pn-test-server

@@ -49,6 +49,8 @@ apt-get install -y \
         virtualenv python3-dev libpq-dev libffi-dev \
         `# Requirements for building LightWAVE` \
         build-essential libcap-dev libflac-dev libseccomp-dev \
+        `# Logging system` \
+        rsyslog \
         `# Other tools required by PhysioNet` \
         zip unzip xfsprogs \
         `# Development and administration tools` \
@@ -230,6 +232,9 @@ systemctl restart postfix
 systemctl disable systemd-timesyncd
 systemctl stop systemd-timesyncd
 
+systemctl enable rsyslog
+systemctl restart rsyslog
+
 systemctl daemon-reload
 systemctl enable emperor.uwsgi
 systemctl restart emperor.uwsgi