Add support for groups in declaration-block-properties-order

[hudochenkov]

Add support for groups in stylelint config:

{
  "rules": {
    "declaration-block-properties-order": [
      {
        "properties": [
          "font-size",
          "font-weight"
        ]
      },
      "display",
      "width",
      "height",
      "color",
      "background",
      "opacity"
    ]
  }
}

Also it fixes #165.

[matype]

@hudochenkov Wow, thanks! Nice work :)

[paazmaya]

This does seem to miss the possibility to use "alphabetical".
http://stylelint.io/user-guide/rules/declaration-block-properties-order/