* make parse() return command id in addition to variable name and value
* introduce parse_kv() wrapper which ignores that id and use it instead
of old parse()
* make parse() compatible with python3 where we got bytes, not string
from the socket so we have to decode it properly before using split()
* expand test_py3.py with simply asyn server which verifies that
osmo_ctrl.py works properly
Change-Id: I599f9f5a18109929f59386ab4416b8bfd75c74d1
566f2a7590