Raspberry Pi Support

[iceychris]

Make LibreASR work on Raspberry Pis.

There already is a Dockerfile which builds fine on my Pi 4.
Loading and running the PyTorch models also works.

But, loading the youtokentome tokenizer model does not work:

chris@rpi4:~ $ docker run -it -v $(pwd):/workspace libreasr-armv7 /bin/bash
root@abf9b8be2d80:/workspace# python3
Python 3.7.3 (default, Jul 25 2020, 13:03:44)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import youtokentome
>>> youtokentome.BPE("tokenizer.yttm-model")
terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted (core dumped)