If no pri or sec docs returned for DNS, sleep for configured amount of time

[punisherVX]

As of 3.5, if SFN has processed all docs, it continually loops through primary and secondary searches for new documents. While this doesn't hurt anything, it just fills up the log with useless text as it returns empty lists. There should be a backoff of X number of minutes (configured via .panrc) with a default of 10 minutes or so. This will minimize the logging and allow for documents to build up.

[zube]

sdndude said: Look into timing for processed 55 events. Configurable setting in .panrc. Ties to #25

[zube]

sdndude said: This is being closed due to the work being done on #78. There probably will never be a downtime if dns-cloud is used.