Using module name as app_name by default

Please, read the subsession **About the First Parameter** from [1].
As you can see, the documentation recommends use the module and
`__name__` is only recommended for single module app.

```python
app = Flask('yourapplication')
app = Flask(__name__.split('.')[0])
```


1 - http://flask.pocoo.org/docs/api/#flask.Flask