Fix including from sub dir

[bramkragten]

The include path is now always relative to the root of the config dir.

Description:

After the first include the path would be based on the included file, so multiple includes from sub dirs would fail.

Should go in a hotfix.

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>

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