Feature Proposal: Support arrays of objects to be merged in the "with" property

[simonmeusel]

See #15
Fixes #12

I've implemented a simple wrapper function for json merge patch to allow arrays.

[coveralls]

Coverage remained the same at 100.0% when pulling 3fd5918 on simonmeusel:merge-arrays into d8c8c07 on epoberezkin:master.

[epoberezkin]

@simonmeusel thanks, I will review over the weekend.

[lakim]

I would love to see this merged.

It is very cumbersome to merge multiple schemas for now.
Here is my use case:

{
  "$merge": {
    "source": {
      "type": "object",
      "properties": {},
      "additionalProperties": false
    },
    "with": [
      {
        "$ref": "definitions/color.json#/definitions/color"
      },
      {
        "$ref": "definitions/font.json#/definitions/font"
      }
    ]
  }
}

Any help needed?