Scan all network interfaces for LIFX bulbs

[amelchio]

Description:

This uses the new aiolifx.LifxScan.scan() method to discover LIFX bulbs.

While unlikely, bulbs may be seen on multiple network interfaces so I reworked the code to connect on each of them.

For feature parity I also updated the manual configuration schema to allow multiple addresses.

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#<home-assistant.io PR number goes here>

Example entry for configuration.yaml (if applicable):

lifx:

lifx:
  light:
    - server: 10.0.9.149
      broadcast: 10.0.9.255
    - server: 10.0.16.5

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.