Add CAV 2016.

bibs/header.bib

@@ -557,6 +557,7 @@
 @STRING{cav02       = cav # ", Copenhagen, Denmark" }
 @STRING{cav07       = cav # ", Berlin, Germany" }
 @STRING{cav13       = cav # ", Saint Petersburg, Russia" }
+@STRING{cav16       = cav # ", Toronto, Ontario" }
 % ---
 @STRING{cp          = "International Conference on Principles and Practice of
                        Constraint Programming (CP)" }