removed comma

lib/letter-avatars.js

@@ -7,7 +7,7 @@ var randomcolor = require('randomcolor');
 module.exports = function(name) {
     var color = randomcolor({
         seed: name,
-        luminosity: 'dark',
+        luminosity: 'dark'
     });
     var letter = name.substring(0, 1).toUpperCase();