Sync up to new zigpy changes.

[Adminiuga]

Implement new zigpy initialization and support for radio lib configuration schemas in https://github.com/zigpy/zigpy/commits/new-zigpy-init/dev

This would allow each radio lib to extend the zigpy configuration schema by adding radio specific configuration options.
Corresponding HA changes are currently in https://github.com/Adminiuga/home-assistant/tree/experimental/new-zigpy-init
I've tested this PR with CC2531 and it seems to work fine

[sanyatuning]

Very nice work. Can I add more config options like rts/cts?

[Adminiuga]

Yep, can add flow control. give me a few.

[Adminiuga]

For flow control, would you ever use "xonxoff" ???

[Adminiuga]

You can now request specific flow control settings by adding flow_control key to configuration dict, eg:

{
    "database_flle": "/config/zigbee.db",
    "device": {
        "path": "auto",
        "baudrate": 115200,
        "flow_control": None   # or "software" for xonxoff or "hardware" for rtscts
    }
}

[Adminiuga]

@sanyatuning review/merge when you have a change. I'd like to add another PR to add a "probe" method to validate the right port is being used. Currently in config flow we go through the whole zigpy initialization to validate the port which is an overkill. The "probe" just going to send one command and on successful response we consider this being the right port

[Hedda]

@Adminiuga Nice! @sanyatuning I guess this type of extension of the zigpy configuration schema by adding radio specific configuration options could also be made work with a "TX Power" (TX_PWR) setting for Power Amplifier (PA) configuration of TI CC modules as requested in #33 for zigpy-cc plus zigpy/zigpy#372 and zigpy/zigpy#364 for zigpy?