In order to be more precise about which screen will be refreshed, the
*POST /screen/{number}/refresh* path operation has been changed to *POST
/screen/{name}/refresh*. It takes a monitor name as the key instead of
an array index.
Instead of hard-coding the list of URLs to open, we'll read it from a
JSON file on the disk. The file contains a mapping of monitor names to
URLs, e.g.
```json
{
"HDMI-1": "http://my.site.one",
"HDMI-2": "http://my.site.two"
}
```
