Private Dictionary support with Private Creator.

[cagylogic]

Current additional tag dictionary by setting doesn't solve private tag and private creator.
To extend it, dicom.privateDictionary is added in setting.

"dicom.privateDictionary": {

    "PRIVATE_CREATOR": {
        "ODDS00XX": {
            "vr": "LO",
            "name": "name and description"
        }
    }
}