Resolve SublimeLinter depreciations. Document need for Dockerfile syntax

[rgant]

Updates for SublimeLinter 4 deprecated properties.

dockerfilelint: Defining 'cls.syntax' has no effect anymore. Use http://www.sublimelinter.com/en/stable/linter_settings.html#selector instead.
dockerfilelint: Defining 'cls.selectors' has no effect anymore. Use http://www.sublimelinter.com/en/stable/linter_settings.html#selector instead.
dockerfilelint: Defining 'cls.version_args' has no effect. Please cleanup and remove these settings.
dockerfilelint: Defining 'cls.version_re' has no effect. Please cleanup and remove these settings.
dockerfilelint: Defining 'cls.version_requirement' has no effect. Please cleanup and remove these settings.
dockerfilelint: Defining 'cls.executable' has no effect. Please cleanup and remove these settings.
dockerfilelint disabled. 'selector' is mandatory in 'cls.defaults'.
See http://www.sublimelinter.com/en/stable/linter_settings.html#selector

[dalisoft]

@rgant Thanks for fixing this issue. I think author really deprecated project or lost access to account or something else.
I Forked your fork and updated docs for easier install.
You can find it at here