Make all Flambe base-models torchscript compatible

[cle-ros]

It would be great if we could extract torchscript models from flambe models, after training. That requires all flambe base models to be compatible with torchscript. After a very superficial attempt to make this work, I found that (at least) some typing instructions in flambe.component are torchscript incompatible.

[jeremyasapp]

100%. We should add a test suite to make sure that is the case, always