DIFF-RS: query parameter 'different' and 'missing' to control if different or missing studies are included in result

[gunterze]

Improves #730

swagger.json

{
    "/aets/{aet}/dimse/{externalAET}/diff/{originalAET}/studies": {
      "get": {
        "tags": [
          "DIMSE-RS",
          "DIFF-RS"
        ],
        "summary": "Compare Studies",
        "operationId": "CompareStudies",
        "produces": [
          "application/dicom+json",
          "application/json"
        ],
        "parameters": [
          "...",
          {
            "name": "different",
            "in": "query",
            "description": "include Studies different at originalAET",
            "type": "boolean",
            "default": "yes"
          },
          {
            "name": "missing",
            "in": "query",
            "description": "include Studies missing at originalAET",
            "type": "boolean",
            "default": "no"
          },
          "..."
        ],
        "..." 
     }
}