fir's API has changed, app list now support paging

Now new app list response support paging and leads to empty app list on old versions.

{
  "apps_count": 2,
  "page_size": 20,
  "items": [
    {
      "id": "57848c46e75e2d5b0200003b",
      "user_id": "56fd41ace75e2d19fa000021",
      "org_id": "57eb6bb7b824a1776a1285d7",
      "type": "android",
      "name": "fir.flight",
      "short": "testflight",
      "bundle_id": "io.github.ryanhoo.firFlight.dev",
      "genre_id": 0,
      "is_opened": true,
      "web_template": "default",
      "custom_market_url": "",
      "has_combo": false,
      "created_at": 1468304454,
      "updated_at": 1475224213,
      "icon_url": "http://firicon.fir.im/4ae734efce7ee934ac11e04cbc5b3468313e48a1?t=1475484462.7413332",
      "master_release": {
        "version": "2.0.0",
        "build": "16082304",
        "release_type": "inhouse",
        "distribution_name": "",
        "supported_platform": null,
        "created_at": 1471947509
      }
    },
    {
      "id": "56fd4e9bf2fc4252c0000005",
      "user_id": "56fd41ace75e2d19fa000021",
      "org_id": "57eb6bb7b824a1776a1285d7",
      "type": "android",
      "name": "fir.flight",
      "short": "firflight",
      "bundle_id": "io.github.ryanhoo.firFlight",
      "genre_id": 0,
      "is_opened": true,
      "web_template": "default",
      "custom_market_url": "",
      "has_combo": false,
      "created_at": 1459441307,
      "updated_at": 1475224215,
      "icon_url": "http://firicon.fir.im/916c9f0fd2a20ee76896a461e0e9432fefc28eb6?t=1475484462.748709",
      "master_release": {
        "version": "2.0.0",
        "build": "16082304",
        "release_type": "inhouse",
        "distribution_name": "",
        "supported_platform": null,
        "created_at": 1471947524
      }
    }
  ]
}