Update pluralize.js (#183)

Author: maxmatthews

pluralize.js

@@ -324,7 +324,8 @@
     ['thief', 'thieves'],
     ['groove', 'grooves'],
     ['pickaxe', 'pickaxes'],
-    ['passerby', 'passersby']
+    ['passerby', 'passersby'],
+    ['canvas', 'canvases']
   ].forEach(function (rule) {
     return pluralize.addIrregularRule(rule[0], rule[1]);
   });