Fix apps loading

Currently, one you add apps in the apps/ directory, you need to call them with 'apps.$app', that sucks. :-) The first commit solves this.

Also, if you get an __init__.pyc file, it will get taken as an app, the second commit fixes that. Maybe the function should only take directories instead of this workaround though.
I'm not a fan of this, this will mostly confuse developers (especially new ones who don't know this subtelty) since your apps won't be prefixed when you import them (ie. `import blog` instead of `import apps.blog`). You'll also get a higher risk of module name clashing with a Python module you might be using.

I would either put all apps in the project root directory, or reference them through their `apps` namespace.