fix: render username even if no url specified

[SethFalco]

When given a JSON Resume with the following, the theme would render an unappealing entry for that profile. This will allow use that username as-is without being linked.

{
  "profiles": [
    {
      "network": "Twitter",
      "username": "neutralthoughts",
      "url": ""
    },
    {
      "network": "SoundCloud",
      "username": "dandymusicnl",
      "url": "https://soundcloud.com/dandymusicnl"
    }
  ]
}

Before

After