Initial commit of a log capture and reporting feature

This adds a new section to the admin panel called "Activity", that
supplies charts, graphs and details about messages entering and leaving
the host.

A new daemon captures details of system mail activity by monitoring
the /var/log/mail.log file, summarizing it into a sqllite database
that's kept in user-data.

conf/miabldap-capture.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=MIAB-LDAP log capture daemon
+ConditionPathExists=/etc/mailinabox.conf
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/python3 %BIN%/management/reporting/capture/capture.py
+ExecReload=/bin/kill -HUP $MAINPID
+
+[Install]
+WantedBy=multi-user.target