Fixed #92. Define the lines variable.

Author: IonicaBizau

lib/index.js

@@ -528,7 +528,7 @@ GitStats.prototype.authors = function (options, callback) {
     var repo = new Gry(options.repo);
     repo.exec("shortlog -s -n --all", function (err, stdout) {
         if (err) { return callback(err); }
-        lines = stdout.split("\n");
+        var lines = stdout.split("\n");
         pieData = stdout.split("\n").map(function (c) {
             var splits = c.split("\t").map(function (cc) {
                 return cc.trim();