legacy modules are not initialized correctly after latest changes

[Adminiuga]

Ha 😆 I made sure explicitly not to use any of the never versions of the lib, because the recent changes made the library unusable on the Xbee Pro S2B platform, due to the commands that you introduced.

2019-01-14 01:05:53 ERROR (MainThread) [homeassistant.config_entries] Error setting up entry /dev/zigbee for zha
Traceback (most recent call last):
  File "/usr/src/app/homeassistant/config_entries.py", line 252, in async_setup
    result = await component.async_setup_entry(hass, self)
  File "/usr/src/app/homeassistant/components/zha/__init__.py", line 158, in async_setup_entry
    await application_controller.startup(auto_form=True)
  File "/usr/local/lib/python3.6/site-packages/zigpy_xbee/zigbee/application.py", line 54, in startup
    ce = await self._api._at_command('CE')
  File "/usr/local/lib/python3.6/site-packages/zigpy_xbee/api.py", line 220, in _at_command
    timeout=AT_COMMAND_TIMEOUT)
  File "/usr/local/lib/python3.6/asyncio/tasks.py", line 358, in wait_for
    return fut.result()
Exception: 2

[Adminiuga]

Legacy XBee modules (S2B and likes) are using separate firmwares for Coordinator/Routers/AT mode/API mode etc and therefore do not support CE command which causes exception during ApplicationController startup