Fix variable which was not defined. Fixes #90.

lib/index.js

@@ -1,4 +1,5 @@
-// Dependencies
+"use strict";
+
 var Ul = require("ul")
   , Abs = require("abs")
   , ReadJson = require("r-json")
@@ -498,7 +499,7 @@ GitStats.prototype.ansiCalendar = function (options, callback) {
           ;
 
         self.iterateDays(options, function (cDay) {
-            cDayObj = graph[cDay];
+            var cDayObj = graph[cDay];
             if (!cDayObj) { return; }
             cal.push([cDay, cDayObj.c]);
         });