adding maintenance info

apache-conf/000-default.conf

@@ -11,6 +11,16 @@
 	ServerAdmin webmaster@localhost
 	DocumentRoot /var/www/html
 
+	# Rewrite-Engine aktivieren
+	RewriteEngine On
+
+	# IP-Adresse des Entwicklers zulassen
+	RewriteCond %{REMOTE_ADDR} !^123\.456\.789\.000$
+
+	# Alles auf die Wartungsseite umleiten
+	RewriteCond %{REQUEST_URI} !/app/maintenance.html$
+	RewriteRule ^ /app/maintenance.html [R=307,L]
+
 	# Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
 	# error, crit, alert, emerg.
 	# It is also possible to configure the loglevel for particular