Registering buffers in Components

[prabhuteja12]

The Component class implements a _register_parameters method that registers the loss' constructor arguments.

This currently works without glitches where Renate manages the state_dict of Learner, Model and others. However, once the move to relying on Lightning for all checkpointing is complete (in #218) this fails as registering the constructor args (say _weight) returns it in the state_dict, and causes an error when restoring the model from checkpoint. The 'fix' for now is going to by changing RenateModule's load_state_dict to use strict=False.

This issue should help cleanup the components code too.