SONAR-2649 Add 'sonar.notifications.delay' to conf/sonar.properties

sonar-application/src/main/assembly/conf/sonar.properties

@@ -133,4 +133,11 @@ sonar.jdbc.timeBetweenEvictionRunsMillis:  30000
 
 # proxy authentication. The 2 following properties are used for HTTP and SOCKS proxies.
 #http.proxyUser=
-#http.proxyPassword=
+#http.proxyPassword=
+
+#---------------------------------------------------------
+# NOTIFICATION SERVICE
+#---------------------------------------------------------
+
+# Delay (in seconds) between processing of notification queue
+sonar.notifications.delay=60