Enhancement for Issue #1074. Added operator overload for pdnslog() to accept a log level when writing out to syslog. Added syslog levels to global lua table which correspond to the second argument in pdnslog. Example: pdnslog(INFO, pdnslog.Info), pdnslog(DEBUG, pdnslog.Debug) , these all correspond to their name in the Urgency enum
Cleaned up commits as seen by Habbie's comment. Updated scripting xml file with a table of new entries. Added some new pdnslog functions within the powerdns-example-script.lua to show new functionality.
Merge pull request #1076 from zmallen/master

Enhancement for Issue #1074.