We only need ethereum libraries for `ethereum_sign_tx` in trezorctl,
and rlp has caused us dependency problems in the past already.
Also we required ethjsonrpc for the same thing but never listed
that dependency anywhere.
That changes now.
This drops the command line options. `libusb` is now required
unconditionally (it's cffi so no harm there). hidapi is an extra.
You either need to install it manually, or specify it in your
requirements.txt like so:
trezor[hidapi] >= 0.9.2
