Add --unsolved flag

[goproslowyo]

Defaults to false
When passed, only download unsolved challenges.
JSON:

.data.solved_by_me

{
  "success": true,
  "data": {
    "id": 2,
    "name": "HumanTwo",
    "value": 50,
    "initial": 500,
    "decay": 100,
    "minimum": 50,
    "description": "...",
    "connection_info": null,
    "category": "Malware",
    "state": "visible",
    "max_attempts": 0,
    "type": "dynamic",
    "type_data": {
      "id": "dynamic",
      "name": "dynamic",
      "templates": {
        "create": "/plugins/dynamic_challenges/assets/create.html",
        "update": "/plugins/dynamic_challenges/assets/update.html",
        "view": "/plugins/dynamic_challenges/assets/view.html"
      },
      "scripts": {
        "create": "/plugins/dynamic_challenges/assets/create.js",
        "update": "/plugins/dynamic_challenges/assets/update.js",
        "view": "/plugins/dynamic_challenges/assets/view.js"
      }
    },
    "solves": 654,
    "solved_by_me": true,
    "attempts": 1,
    "files": [
      "/files/671ca0608e31fe1e67d84ed9e2c05a09/human2.aspx_iocs.zip"
    ],
    "tags": ["easy"],
    "hints": [],
    "view": ""
  }
}