Test output to HTML view

[takluyver]

Test outputs will be in JSON files, something along the lines of:

{
  "kernel_name": "python",
  "variant": "pip_stable",
  "kernel_version": "5.1",
  "features": {
    "kernel_info": "passed",
    ...
  }
}

We will want to use this to build a nice HTML page listing kernels and their statuses.