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.

tests/bin/m-debug.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+cd "$(dirname "$0")/../../management" || exit 1
+systemctl stop mailinabox
+source /usr/local/lib/mailinabox/env/bin/activate
+export DEBUG=1
+export FLASK_ENV=development
+if ! systemctl is-active --quiet miabldap-capture; then
+    export CAPTURE_STORAGE_ROOT=/mailinabox/management/reporting/capture/tests
+fi
+python3 --version
+python3 ./daemon.py