Color duplicates reporting should follow format of other reports

[bartveneman]

The color duplicates report is now a single array of objects, but for other reports of similar types we have an object with total, totalUnique and unique. For duplicates total and totalUnique will always be the same, since it is extracted from colors.unique.
Currently the total or totalUnique property is missing, so it is not easy to display it in Wallace-CLI, on projectwallace.com or to test for it easily in Gromit-CLI.

Current format:

"duplicates": [
  {
    "value": "#000",
    "count": 2,
    "aliases": [
    {
      "count": 1,
      "value": "#000"
    }, 
    {
      "count": 1,
      "value": "black"
    }]
  }
]

Proposed format:

"duplicates": {
  "total": 1,
  "totalUnique": 1,
  "unique": [
    {
      "value": "#000",
      "count": 2,
      "aliases": [
      {
        "count": 1,
        "value": "#000"
      }, 
      {
        "count": 1,
        "value": "black"
      }]
    }
  ]
}