Improving icloud device tracker

[evgeniy-khatko]

Description:

1. Adding max_interval, gps_accuracy_threshold config parameters to icloud traker.
2. Fixing device_tracker.icloud_update to actually update devices states.

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.io#5240

Example entry for configuration.yaml (if applicable):

device_tracker:
  - platform: icloud
    username: email@email.com
    password: !secret pwd
    max_interval: 10
    gps_accuracy_threshold: 1000

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

(home-assistant) 186590cfe02f:home-assistant evgenyk$ flake8 homeassistant/components/device_tracker/icloud.py 
(home-assistant) 186590cfe02f:home-assistant evgenyk$ pylint homeassistant/components/device_tracker/icloud.py
Using config file /Volumes/work/home/home-assistant/pylintrc

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

(home-assistant) 186590cfe02f:home-assistant evgenyk$ pydocstyle homeassistant/components/device_tracker/icloud.py
(home-assistant) 186590cfe02f:home-assistant evgenyk$

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

• Documentation added/updated in home-assistant.github.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 dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works. -> Component does not have unit tests yet. This might be a matter for next commit.