ericf#253 Fix issue with always defined defaultLayout property which …

…always render default view, but the one that was specified to render.

lib/express-handlebars.js

@@ -26,7 +26,7 @@ function ExpressHandlebars(config) {
         extname        : '.handlebars',
         layoutsDir     : undefined, // Default layouts directory is relative to `express settings.view` + `layouts/`
         partialsDir    : undefined, // Default partials directory is relative to `express settings.view` + `partials/`
-        defaultLayout  : 'main',
+        defaultLayout  : undefined,
         helpers        : undefined,
         compilerOptions: undefined,
     }, config);