Missing check of attributes in facade_attrs

[MaGering]

There is no consequence if I add attributes of a component which do not appear in its class to the csv files in facade_attrs.

I would expect a test or error message which ensure that a valid attribute is passed.

[MaGering]

The problem addressed in this issue led to: #86

[jnnr]

We can address this as soon as facades are dataclasses (oemof/oemof-tabular#44), which will allow us to drop facade_attrs documented manually in csv files.