byte parameters and command names should be used as is

[vcalv]

for example:

print(plumbum.local['echo'](b'test'))

should result in

test

but instead it results in:

b'test'

byte objects are not even supported in command names:

plumbum.local[b'echo']

results in a type error

TypeError: a bytes-like object is required, not 'str'

in plumbum/machines/local.py:243