Add /sbin to launchd PATH

[andersonshatch]

Description:

On macOS, ping resides in /sbin, so when running hass with launchd, it needs to be available on the PATH for ping sensors to function

Related issue (if applicable): fixes #

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):

binary_sensor:
  - platform: ping
    host: 192.168.0.1

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

[fabaff]

Looks good to me but I'm not a macOS user.

[frenck]

/sbin should be further down the path. E.g., the user should be able to override an executable in the lookup path by placing a program in /usr/local/bin for example.